I don't have OTFC, and honestly wouldn't care about it since I have CSSS which is obsessively consistent. The only case where I might need to look beyond CSSS is when I need to write some exposed/virtuosic lines; a dedicated library for that purpose would then be a more logical option..
I ended up getting Orchestral Tools First Chairs, but haven't spent enough time with it to give any definite judgement, so I'll just share two quick thoughts.
The bad news is that it is quirky and a bit harsh for the stuff I'm currently working on. The good news is that it brings a whole different element of natural sounding definition and, yes, harshness that I don't have with my existing strings. So it gives me a sound I was lacking and am looking forward to exploring, but I just haven't needed it for current projects.
I plan to get CSSS as well, and I imagine that will be my workhorse and I'll know it can reliably get the job done. OTFC will be more for special colors, like "let's try experimenting with adding this and see how it sounds". Also, it'll supply the solo bass that CSSS doesn't have, and be my go-to for certain styles of vigorous attack and crunchy shorts.