, like you, was all excited about LEDs, no heat issues etc. I purchased two of the Blue panels, like these for a little test before I jumped in with both feet.
http://cgi.ebay.com/All-RED-225-LED-...4.c0.m14.l1262
And tried to use them for Vegging some ladies, I very quickly abandoned them all together and after doing some heavy research into LEDs vs HPS the claims made by the LED sales guys didnt really add up. There are some fabulous articles about growing with LEDs, guys not growing bud but other plants that did some serious scientific research in their own labs to determine LEDs have uses but not by themselves for growing.
Couple that with a little test of my own between a 4 small plants, 2 under CFLs and 2 under LEDs, same strain, same cloning etc. After about 2-3 weeks the CFL girls were doing well, the LED girls were not. I abandoned my test and started working out heating issues with CFLs as my longer term solution for veg.
Now the light you are talking about is equivalent to a 300-400 watt HPS and we are talking flower not veg, so you may find significantly different results, I just found for the money, it was better to go the tried and true method, I have a 600 HPS in a home made cool tube and it works great for about the same price as the LED. But of course I have venting and filtering to deal with which matches the cost of about two of the LEDs (which they claim is about 600-800 HPS watts).
Dont get me wrong, you can grow bud under LEDs, just not as dense or potent bud under LEDs as other options. At least that was the conclusion to my research.
To your credit, it did remind me about my LEDs and I am going to go dig them up and add them to a small Veg chamber I have with CFLS already in it. Spent the money, might as well get whatever I can out of the lights, even as a supplement.
Are you sure ventalation isnt possible for you?
I'd love to hear how the LED works out for you if thats the way you go. Happy growing.