I have a Neu 1521/1.5Y that can handle 10S and it will spin at around 44000rpm with 12S. The point of a controller that can handle 12S or more is to use less AMPs. It will give you better run times, plus you can use good 2200-2500mAh packs. This is the main reason why I keep asking for it.
I see - well, that's awesome. I've always been worried about the higher rpms when you go to the HV stuff. But your logic is exactly why I am going with the 6s in my XT8 so I'm with you there. Reduce the amps and increase the voltage for better efficiency and temp control. I just didn't know how far to take it.