I had the 4X (a couple times) and a 1000. The 1000 is a very good board, but the keys are nowhere near the 4. The girth is very large and I felt was more difficult to transport. As a piano player your are, not sure you would like the keys. A lot of guys on here love the board though.
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Yamaha 920 / Yamaha Stagepas 100 BTRs / Senn e935 - LIVE
Roland RD 2000 / Tascam DP24sd / ATEM switcher - STUDIO