I generally don't like the A/B mic in OT libraries. Iinm they are figure 8's so there's quite a bit of 'room'. The Tree mic's have less 'room', just right to my ears!
I generally don't either as a main mic, I used it in the SF example to fit it into the soupy air lyndhurst sound, but generally I work mic mixes in a certain way.
I'll start with a "main" mic, like the tree. Then if I want to add distance I blend it with the AB or surround. the key difference being AB if I want narrow stereo image, surround if I want wider stereo image.
a great example is using a bit of AB to add distance and lushness to strings while using a surround heavy mic mix on brass to give the brass width. similarly one might want to use more AB on woodwinds and percussion then a more even amount of SURR and AB with strings