I just didn't see anything in that video or on their website that would make me think it can do much that I can't already do - and the bit about needing to hit a button to determine whether the knob is going to control a horizontal/vertical/rotary knob seems a bit of a joke. Any mouse or trackball with a scroll wheel or ring can do that already (at least on Mac it does), and you don't need to hit any buttons or even click on anything first.
The Kensington Expert Mouse trackball has four buttons and a scroll ring (like the scroll wheel on a mouse). So by default, turning the scroll ring will be like turning an on-screen control (knob, slider, whatever) whenever the cursor hovers above it - no need to click first, and it will correctly adjust the control whether it's a rotary knob or a slider / fader. Since your finger is right there anyway, it takes less effort and time than reaching for a hardware knob. Just move the cursor around the screen to hover over any fader, knob, slider, whatever - and then spin the ring.
If you just want a hardware knob and don't want to mess with trackballs, mouse wheels, etc. then grab a Griffin PowerMate. I used to have one, and I believe it just duplicates the native scroll wheel functionality that your computer already has, but with a nice aluminum knob. I don't think you need to mess with their fiddly software to just get that functionality, just plug it into USB and you should be knobbing away at whatever the cursor is hovering over, no need to hit a button to decide between vertical, horizontal, or rotary. Which is good, because I think the software is deprecated and no longer being updated for new versions of MacOS - but it's a cheap way to see if an actual hardware knob can duplicate the scroll wheel, and if that's of any use to you. But it's been a while since I had one - all it did was duplicate the scroll ring of my trackball, which I already had my finger on, so....
$45.
https://griffintechnology.com/us/device/laptops/powermate
But back to the Expert Mouse trackball - without even installing the driver software, the lower-left button is normal-click and the lower-right button is right-click, so in Logic that gives me three tools right there, so I've never actually used Logic's tool selector palette -
EVER. Normal click is select, command-click is scissors, and right click is fade tool. Done.
But the Expert Mouse has four buttons, so if you install the software you can assign whatever you want to any of the four, so the two at the top could execute key commands, etc., and it supports "chording", where you hit both of the bottom or top buttons at the same time, so that's two more key commands right there. These can be assigned to send any combination of keys, or even type a text string if you want.
That thing on the Control Master about jumping the cursor to hot spots across multiple screens looks kind of neat, but there used to be a way, I forget if it was in the older Kensington trackball driver software or in QuicKeys, that let you designate any number of "hot spots" across any number of displays, and when holding a modifier key and moving the cursor, the cursor would snap to those spots - like "snap to grid" for mouse positioning. I kind of stopped using that feature a decade ago as I didn't need it - my dexterity with the trackball is just too good! Unlike with a mouse, with a trackball you can "throw" the cursor across multiple hi-pixel-count displays with a single brisk swipe at the ball, like playing the old Missile Command arcade game, whereas with a mouse you often need to "pedal" the mouse by moving it, lifting it, moving it again, etc. The Kensington trackballs have got a finely-tuned acceleration curve, so it's easy to "sling" the cursor across a big display but still have very fine control when moving the cursor slowly, and this is adjustable within their software - but I don't even use their software. I just plug it in to the Mac and go.
If you've never tried one, it might be worth the $100. Some folks prefer a track pad or mouse, but the scroll ring on the trackball is big and chunky and rubberized, and it's always been easier for me to use that as opposed to the little scroll wheels on a mouse (or the touch-slider-thingie on the Apple Magic Mouse), but it's all personal preference - I've been using these trackballs for 25+ years and when I try to use a mouse or trackpad I fumble like a child.
But that's just the basic stuff you get with an Expert Mouse for like the last 15 years, and not really what you're talking about. Most functions that you mentioned can be done from the keyboard, depending on what DAW you use. In Logic I almost never use the mouse / trackball for anything other than adjusting virtual knobs/sliders with the scroll wheel and selecting and dragging regions / notes on the screen, and even a lot of that I do from the keyboard. I don't ever manually pull down on menus to get to an edit command or whatever, that stuff can all be assigned to a key. Zooming, locating, creating markers, transposing notes by semitone or octave in the key editor, moving events or adjusting event lengths by ticks/16th/beat/bar/8 bar amounts, browse plugin / channel strip settings, etc. - that's all key command stuff - and in Logic any key command can be triggered by incoming MIDI events, so you can build a crazy setup with iPads, TouchOSC devices, or the buttons on hardware like a LaunchControl XL or something.
There's also devices like the X-Keys USB devices from PI Engineering. I used to have some of these back in the day. These are like super-extended user-configurable USB keyboards that can be programmed to trigger any key or combination of keys from any of their buttons, and you can print custom labels and slip them under the clear key caps. Pretty slick if you don't want to memorize complex key combinations or use an iPad that only has "virtual" buttons - these things have chunky mechanical buttons and they're pretty bad ass. Sort of like a hardware button version of Hans' touchscreen for triggering key commands in Cubase.
https://xkeys.com
Browsing Kontakt instruments can be a little less fantastic from the keyboard; for the most part you can navigate within the Files browser with arrow keys and load instruments by hitting Enter, but in the Libraries pane it often still requires some clicking. I do wish they'd implement a key command for the arrow buttons at the top of the Instrument that discard the currently loaded Instrument and load the next / previous Instrument in the current folder. That's one of the few things I actually need to click on in Kontakt, besides the knobs on the Instrument GUI or whatever.
I've had most of these devices, including things like the Euphonix MC-Control with its little touchscreen, iPads with TouchOSC, X-Keys, etc. But in the end, all these things are doing is giving you a different way to trigger key commands that already exist or can be user-configured in your DAW software - they don't
add any new functionality, they just give you a different way to access existing functionality. So I just wind up creating and memorizing the key commands, rather than looking down at a touch screen with colorful virtual buttons that will do nothing more than trigger "command-option-shift-G" or whatever. But it's personal preference. I just like a clean, uncluttered work surface with as few moving parts as possible. So now my only moving parts are the scroll ring on the trackball, my Mac keyboard, and my ever-evolving list of Logic key commands.
But - my early years using computers for music were in the days before the mouse (!), when
everything had to be done by typing a key. R for record, T for transpose, etc. I'm talking DOS 3.1, Commodore-64, etc. So configuring and memorizing long lists of key commands is second nature to me - but for those who came up in the mouse era this might not feel so natural.
Horses for courses.