Re cutouts, I've never ridden a seat with one, would be interesting to seriously try one sometime, although we have to be realistic that one cutout model could be very very different to another.
I suspect I would like a c17 cutout, as my regular c17 is good, but would be nice with more flex that maybe comes with a cutout.
we've also a Terry seat in the household, my wife found it fine, as my daughter who uses it now. All in all though, my wife finds the b17 the most comfortable.