Phatter! Ha, what exactly do you mean by that?
I know a guy who has a Gaia, the stuff he's done with it sounds great. I've mixed him live and it sounds really nice over a big PA, fat and juicy. If you go here: http://www.supermelody.com/
and click on the listen tab the track Tinder Hearted you can hear it. That's the arpeggiator on the Gaia playing the looped bass riff.
Anyway, both those synths are pretty good. The Gaia has some extra options like USB for better integration with a computer setup and more sounds courtesy of the sampled waveforms. If you're into either of those things or you just like buying things new so you get a warranty then they're good reasons to go with the Gaia. They're both pretty similar though so just go with whichever one draws you to it more.