I have a par38 over my frag tank, which is about a 10G cube. In my experience:
-All of my zoas do very well
-Majority of my palys end up bleaching and going back under the T5's in my display
-2/3 of my SPS do very well, but others experience bleaching
-The only LPS that I have tried are chalices and acans, which seem to fare well