Hi jessman and welcome to the forum. A few bike mags have tested the Gixxers head to head but unfortunately don’t quote wheelies as their landmarks. Shame really as it’s ‘real world’ and it’s fun! I guess for wheelieability (made that word up myself) the 750 has got the edge, but I’m open to being slapped down on this one. Stoppies has to boil down to the braking system and I believe the 600 wins with its great, progressive anchors. As for doughnuts, well my mate’s old Z650 can still cut it with the best, just price up the tyres on the Gixxers to see what’s the cheapest to replace!