Agree with him (yes he does know his stuff well!), if they are dimmable, then there shouldn't be a problem with it being on the glass. Great that you're not rushing your decision
. I have a 6 bulb T5 HO fixture on my 70 and the legs aren't stable/don't fit the frame when they are the highest, so they have to be about 4 inches from the water (if that makes sense). I have to put all types of corals on the sand or close to the bottom or else they get fried...So I'm probably going to go with the hanging kit. LEDs seem like the best option for your situation.