-
Hmm, I've never actually skidded in a fixed crit so maybe the powertap hub could work.
It's not just skidding though. I once gave a decent amount of resistance through the pedals of my track bike because I wanted to make sure I made the ramp at the velodrome, and the rear hub started to unwind itself. Not a nice feeling. So slowing down vigorously is enough, and I'm assuming in a fixed crit you may need to slam on the anchors occasionally.
Powertap track hub is my favoured option for track and for fixed gear bikes. I have six of them. The only downside is that if you try to back-pedal too hard, or skid, the internals start unwinding themselves, which is bad. If you can avoid that, they're brilliant. But the 'no back-pedalling/resisting forward motion too hard' thing might make them unviable for fixed crits. In which case, you're back to a spider or crank arm based option.