+1 for the control esc and motor ,for a class that is faster than 540,yet slower than the current 17.5.
The 21.5s are still subjective to esc wars too,the punch is just lower.

Like all changes, people need to do the R&D at club level first,then take it progressively higher on the event scale. E.G : CC, Summer Nats,Stares, Nationals.

For the club racer,who wants to be competitive - on a budget,it just isn't happening at present. You save the $ to go brushless, then 3-6 months later, you're off the pace.This can be quite disheartening to guys ,who try their best ,week in,week out.
Skill is important, but can't help when the front wheels are pointed straight.......
I love the simple setting adjustments on the SPX,but how much longer can it keep me at the front ??
The mini system works great for that class, just a shame the tyres are so damn frustrating !!