you want a R2 killer, but in what aspects? acceleration? hill climbing? range?
i’d say, at the moment, the R2 is by far the best prebuilt board on the market. the acceleration on the thing is incredible.
having said that, it’s still a preconfigured board. you may need a board to out perform in certain aspects, while not needing others.
with a diy board, you will still get to tune up whatever aspect you need to. so, need more torque? change the gearing. need more range? build a larger pack.