The rack arm difference is length, not height. I'm sure you can look around with Google and find actual length measurements.
As for mods, I've done very little. I don't know what the tape mid, so I don't think I've done that. I use the Roland vh11 top with the strike controller (original spring, no mod, works perfectly) for hihat because the edge sensor is garbage. I use the strike hat top as a splash, and I made a cloning y cable so the cymbal on the far right is the exact same as my hihats for when I want to play open handed. I have splitters on toms 1 2 and 3.
I did have to get a new module on an rma because mine had pretty much no volume, but that was quick and easy.
Like my post in the mimic topic, there are a few warts, but it's been pretty awesome for me