Beyond Compare 3.3.3 works well on Mac OS X Lion with CrossOver 10.1.1.
I am aware of one small and one medium issue:
Small issue: the keyboard shortcuts in Beyond Compare's dropdown menus have a square character in them. The menu option and keyboard shortcuts work just fine, the square character just makes it look funny.
Medium issue: Sometimes Beyond Compare's wineloader process uses 40% of cpu and won't stop unless I shut down CrossOver. It happens when I have Beyond Compare open with a window that's diffing 2 files. For a while everything is fine, the wineloader process isn't using much cpu at all. Then wineloader starts using 40%, I don't know why: I haven't done anything with Beyond Compare or any other CrossOver/wine program, and the Beyond Compare window is just sitting there, nothing is changing on it.
When I close the Beyond Compare window wineloader stays at 40% - it is apparently unaffected by closing the Beyond Compare window. Quitting CrossOver "fixes" it; the wineloader process goes away.