I've always used this game as my benchmark for testing game compatibility and functionality of new versions of CX/CXG and this game continues to work perfectly on my main test system (C2D MacBook, GMA 950, 10.6.8) with CXG 10.1.x.
I've started to also play this game using the unofficial HD patch available here: http://sites.google.com/site/heroes3hd/
This mod has with it a patched .exe for widescreen resolutions, and also works without problems in CXG (in my experience).