Got an RK-9000RE myself. It's been rock solid for a good while now. Admittedly, my indicator LEDs seem to be bugging out a bit, but there doesn't seem to be any ill effect on the use of the board otherwise.
I recommended my buddy get one as well when it was on sale. His did end up having issues (again with the indicator LEDs as it turned out). His indicator LEDs would cut out/dim/etc, but it would actually affect the operation of the board oddly enough. Anyways, it turned out to be a super easy fix (resolder the LEDs) and while I was at it, I resoldered the usb connector to the PCB to ensure he never had any issue with it in the future.
The RK-9000 is a nice keyboard, even with it's issues. If you do encounter issues with it, and have any electronic handywork experience, you should have no issues repairing it.