Temps are the same with the hps, about 10 deg warmer than the room. Currently 70f (morning) in the cab, the hottest being 78f (probably the first hour it was on) . Good times!
Ballasts produce heat and most lighting systems have the ballast separate from the bulb base and usually outside of their grow space but with proper ventilation you should be fine .
Damn! I like that. I never knew that ballast produce excess heat. Man I feel stupid. My set up was 400w mag ballast sunsystem. Now that I know this, Im going separate from now on. HPS rules. Going to cfl and led soon though, I got to try it.