Heat is the biggest disadvantage to the CF's, but as I stated with mine, by leaving the top completely uncovered and allowing the heat to freely rise out, it also makes a really cool room accent lamp provided the lights CF's are at least 6" below the open-top so they don't blind people. I can see if I can get a pic tonight with my new digi. If you want to really fight the heat and have the top covered, PC case fans can easily be rigged up. I would think two would suffice if placed with the intake in the lower left corner and outake in the upper right corner of the back panel. If you wanted to go with 3 fans, I'd suggest going for 2 outake and 1 intake.
Regarding the home depot bulbs, those are where all mine are from. I use the Philips 23W Daylight Spiral CF from home depot. Regarding disadvantages of these bulbs, yes (kind of), there is one I can think of. When you buy a CF from the local fish store that is labeled for aquarium plants, you are going to pay more for the same wattage for a couple benefits. The LFS CF should be a sepctrum(s) best suited for plant growth. The packaging will also (in most cases) tell you if it's a 6500K, 5000K, 3500K, etc.. (5500K-6500K being best for plants). Those are the main advantages I can think of for spending more for the LFS CF. I feel mostly your paying for packaging and advertising, but that's just my oppinion.
Now, for the bulbs you can get cheap at Home depot, some are better than others. The bad news is the better ones are a fair bit more expensive than the less beneficial CF's. The good news is it is still much cheaper than buying CF's from the LFS. Problem with the good and bad at the depot is none (that I have seen) give you the light temp (3500K, 6500K). If you buy plain old CF's, either labeled as 'soft white' or not specifying at all, it is usually a much lower temp rating, something like 3500K I believe. I originally tried 138W of these (6x23W) and they made everything look yellow or golden. It looked cool, but I knew it wasn't the best spectrum for the plants. It seemed to work for the plants fine enough (compared to my old setup at least), but I eventually saw those daylight CF's at home Depot and bought 6 of them. They are more expensive than the soft-white (daylight=$10ea, soft white=$17 for 3 OR $6ea(CAD)), but they give off the same white light as my previous PowerGlo's. The 20W Powerglo's cost me $20ea and I could fit a max of 3 for 60W. With CPF's being so small and efficient, I think they are a better and more economical choice for planted tank lovers with tight pockets (like me). What size tank are you looking to do this for? Let me know the capacity and dimensions and I'll let you know what I tink would work well for you, your plants, and your pocket.
Colin