I have a pico office tank (.75-1g cube) that is ambient temperature. Lighting is 2x 7w PC 6700k, and I have never taken the temperature in the tank, but it can't be more than 76 degrees. (I will take my temp probe into work tomorrow and edit this post to add the temp).
I have had a small 6 polyp zoa frag in there since the begining (10/2005). It is doing 'fine', that is it is always open, looking good. It just hasnt grown yet, and it is mostly brown with a small green center, not at all like the mother colony in my 6g nano cube. I ran the pico with just 7w of PC until a few weeks ago when I bought a second lamp. The zoas are slightly larger now, a bit more green in the middle, and I hope they decide to multiply soon.
Based on my observations, light is more of a factor than temp.