In addition to all the comments from Advantage fans here, I also wanted to add that Kinesis has been an awesome company. I tweeted about some mods I made to my Advantage keyboard a long time ago, and they invited me to their office and donated a bunch of keyboards to the nonprofit I work for, to give as prizes to students (even before they launched the gaming-focused brand).
I delete my really old tweets, but it was actually to make the Advantage Bluetooth-enabled!
I added a Bluetooth keyboard converter, LiPo, and charge controller inside the case.
Unfortunately the Sparkfun documentation for the charge controller implied that it would prevent undervolting which wasn't true, and the battery died. They fixed the documentation but wouldn't send me a replacement battery. I didn't have the money for a new one at the time and reverted it.
