CarbideBob is 100% correct. Moving lots of carbide in the past few years i've been exposed to some interesting stuff.
I don't doubt that you have.
Nonetheless, I have two decades of my own experience to draw on, and I've been using capto alongside steep taper for over half of that time.
I do not do high speed - the fastest spindle on my floor is 12k - but I do lot of heavy machining in tough materials, on medium to large machines, and there is absolutely no situation where I would choose steep taper over capto if I had the choice.
I'd take a 50BBT over a C6, but I would take the C6 over a plain 50, and I would take C8 over either of them.
I'm not sure I'd ever be able to really leverage a C10, but I'd like to try!