Well... it sounds like you've got a few runs under your belt, that's my impression at least. I've never had high heat ruin the high before, nor have I ever used CO2, nor have I used LEDs for growing, so the only thing I can really discuss with any measure of intelligence is the heat issue. I've run Bubba Kush and she's always been a good girl, very popular among the tokers. So.. it's hard *not* to blame the LEDs, isn't it?
I'd be running this question in the LED forum. We've got a few cats here who have got their grows pretty well dialed in and are pulling pretty decent crops. I am now drawing a complete and total blank on the guy who's posts I like to follow on this subject, too. Bump this in a day or three and maybe it'll be in my head again.
Edit* Ha! I remembered because he liked one of my posts. @tags420 <--- that's the guy whose posts you want to go read.