The website states that you can reprogram any key you wish, even having the Backspace instead of the left spacebar.

http://www.trulyergonomic.com/benefits.html#Programmability http://www.trulyergonomic.com/options.html#Model-109

There's a video on youtube of someone typing on a Kinesis Advantage, where one can see a lot of wrist adduction to reach the tab key. The Maltron keyboard might be a better option for heavy tab-key users.