They are exceptionally skilled riders with a lot of experience on similar hardware.
I believe that if you gave Mario and Reggie a well tuned 4wd with their remote of choice and enough power, and they took the time to really feel out how to get the most out of 4wd, what bias they like, and they ran with it for a while even if it felt weird for the first few sessions, they could be even faster. That’s because no matter how sticky your tires are, physics just says having braking power in the front (whatever bias you may prefer) can offer higher total braking grip, or at least make it way easier to utilize the same braking grip. RWD seems to work great braking on BRPs, but if you are on an inferior tire or just a surface that isn’t that sticky, you are definitely giving up some potential. Even in perfect conditions 4WD should move the maximum possible braking grip higher, giving you more options to try different lines and the ability to only brake later even on the same line - I believe 4WD is an advantage on any track that has short - medium track turns. Long track probably doesn’t help as much.
Also I just don’t want to deal with duty cycle control personally. I want smooth torque control, because I believe it helps me be smoother at high power, which ultimately results in better confidence in the setup and myself, and better lap times. Duty cycle control works for many, I personally don’t want to learn it though. I think torque control is more intuitive.
And lastly there’s little nuances like torque vectoring and such, only possible to implement when receiver pwm directly controls torque, or if you have an open source ESC that you can command in ways other than PWM. I’ll be implementing it for my VESC setup this summer. I believe that’s another way to utilize grip more efficiently. I believe either torque vectoring or a locked / limited slip differential goes a long way in improving the ability to put down power in a turn. The SSS had a locked diff and I think that was a brilliant idea that wasn’t too hard to implement. That said, while I haven’t tried a locked diff, in theory it should make turning more effort, while torque vectoring can be used to give a power steering effect. Not sure if the locked diff can actually be felt or not, but might be worth a try putting that single motor setup on the GTA or V6 chassis if clearances allow? A locked diff setup with power steering effect sounds pretty dope.
I foresee the longer term future on 4WD with torque vectoring. I think inrunners are part of it, but lower KV would be great so they’d be easier to drive. Then it can be made high voltage as well. But it also needs high amp VESC prices come down a bit more to really start making sense.
Or if hobbywing made a max4 or max5 ESC where pwm controls phase amps directly just like on vesc, with a comparable smoothness to vesc, and the ability to make my smart pwm splitter that does torque vectoring, I’d be all in on that one and ready to jump ship from VESC.
And it’s also not cooked 
