I painted the back of my 90g with:
It worked swell. I would suggest getting one of those mini rollers and take your time. Put a coat on, let it set and *fully* dry before putting the next coat on...repeat 3-4x. I have had no problems with chipping or it not staying firmly placed on the glass. In fact, it dried quite nicely, looks very neat and is clean.
I would say get the semi gloss though as I have found that putting my hands in the tank and occasionally dripping down the back of the tank will leave white drip marks that don't go away all that easy on the flat that I used. They will go away, just takes a few passes and I don't think that semi will have the same small difficulty. If this is going on the back of your tank, remember, the glare might not be much of an issue as you will have a film of algae or coralline growing back there.
Good luck.
-Ken