I've been watching this thread now for a while. The real issue as I see it is the definition of performance for brakes.
The key parameters are:
Pad longevity - on the track it's about getting through an enduro. On the street it's lasting until the end of warranty. Similar goals, different issues.
Rigidity - pedal feel and brake modulation is really important when you're trail-braking, not so much when you're approaching a stop sign.
Maintainability - swapping pads at the track means easy access to the pads themselves. It's not a factor for the dealer or independent mechanic, in fact for them slower might just be better.
Cost - OEM is all about cost. Simpler structures cost less.
Endurance - Simpler stuff lasts longer. Duh.
So what does this mean as far as 6-piston brakes vs. floating caliper single piston brakes?
The floating caliper brakes are cheaper, and with small pads (shorter life) they're as rigid as multi-pot calipers. With fewer parts to go wrong, they'll last longer too. As to stopping power, they're just fine.
Multi-piston brakes are more demanding as far as rotor run-out is concerned - they don't compensate automatically for wobbly wheel bearings. They're much quicker to change pads on, and they have the capacity to hold much larger pads without the risk of the pads actually bending under load.
As for cooling and actual braking power, the two designs will be similar in performance. Cooling is more a factor of air flow and rotor design than the caliper layout.
So, it's really a case of horses for courses. Multi-pots go on race cars because you can run larger pads and change them faster. Floating calipers go on OEM setups because they're cheaper to build, they last longer in long-term service and they are more forgiving of rotor runout issues.
As far as how well your brakes will do at getting you stopped the next time you use them, either on the track or in traffic, is more a function of rotor design and pad selection than the number of pistons.