It looks like heat issue is going to be about the same for both systems. The T5 HO's do get pretty warm. I would be tempted to look at a 400w cool tube system.
400 watt HPS GROW LIGHT GLASS COOL TUBE Reflector 400w - eBay (item 180180080284 end time Mar-12-08 14:25:49 PDT)

Or go to a strictly T5 system.