I am looking into getting a electronic drum kit that I can use for both recreational use (like an acoustic drum set) and for Rock Band 4, preferably with pro-cymbal support.
I was thinking about getting an ION drum kit, but I have found this comment amongst others in this thread.
Q: I play Rock Band with my ION Drum Kit. Will the ION Drum Kit, as well as other MIDI drum kits, be compatible with Rock Band 4?
A: The short answer is “no, not at launch.” Our first priority is to make sure that the core Rock Band legacy instruments be compatible on day one when Rock Band 4 launches – and they will be! If you want to see ION support in Rock Band 4, you can let ION Audio know by contacting them here: http://www.ionaudio.com/support/. We know that many of you play Rock Band using these peripherals, and we are actively working on finding a solution to this compatibility issue.
Is there an alternative to playing an e-kit with Rock Band 4 on Xbox One?