Rev limit controlled by the ESC would solve nearly all the stock issues. The 2018/2019 European Touring Car Series(ETS) is running a brand new 17.5t class using a MuchMore ESC, I believe they have set the limit at 19,000rpm via special software and a fixed gear ratio, I don't think a controlled gear ratio is practical for club racing though.
Yes and no.... when working with an handout motor indeed the differences will be minimized. If people can bring in their own motors then the war on torque will start....