I bought one. Amazing piece of kit.
The popularity of this will accelerate the development of other products from Behringer and the like. I too was worried about the battery as a sealed unit, but the lifespan for these is likely to be less than a decade, and so for that I think it's OK. I bought the guitar version as I'm back to playing the thin stringer, but it works flawlessly for bass too. I'm yet to try it on the EUB, that's tomorrow's experiment!