The g402 feels very similar, but uses a different sensor type.
The G502 has a different body, with more of a hump in the back, but uses an upgraded version of the same sensor engine (no angle-snapping, though) (yes, there are some other tweaks, but they are minor in comparison). If you palm grip, the body style should work fine.
Up to 1250 DPI, the G300 is a good mouse. The non-centered sensor gets people all in a tizzy, but I got used to that within hours, myself; and with a claw grip, could easily reach all the buttons (can't do that on my G402 :\). That it didn't track well at 2000-2500 DPI was why I replaced mine--if it had better tracking at over half the rated DPI, I'd be using it right now.