What exactly was changed about the cpu? Isn't a GX practically the same architecture (and performance per mhz, ignoring SIMD) as a CX?
Before I go in depth ninzel is pretty much right about the red steel obersvation on the models. The look makes em look like cutouts at a distance due to Aura the ubisoft team wanted to do. In motion I'm assuming this actually would look pretty nifty but in stills (why bother with next gen material) it ends up looking assy to some. Fox I've said some of the changes they did in various threads littered around the forums, but no harm in saying them here.
Cache size both L1(128k unconfirmed how) and L2(512) are beefier than the gecko. Source said the cpu ran faster than the 750GX, though didn't disclose what bencharking was done. Memory addressing was tweaked as well but as you notice not really specific. It wasn't a simple die shrink either as even with the shrink there is ample room for nintendo to make even more adjustments with space left. Considering the three things along with power consumption tweaks nintendo has been doing I wouldn't be surpried if there was a little more to the cpu we don't know.