I would recommend away from kessil right now. 35W for 250 bucks? maybe for $125. Go find a 240 watt, or 180 watt led light, you can pick up some good ones for like 260 bucks (less for the 180W). They have multiple spectra (including UV), a much wider foot print, and are fantastic to use as an supplement (as I do). I have a 500W LED (3w x 168 diodes) helping out a 1000W HPS. I Love the results so far. I can't go all LED cuz I need the HID for heat (why spend watts on a heater, when you can get a light that heats?). Don't go crazy over name brand LEDs, just take a good look around, and you will begin to be able to sort out the good from the bad. I own a blackstar led light, (ebay, amazon, and they have a website). I thought they were shady at first cuz their prices were low. I saw them in person to see the lights in action first, and was satisfied. I have no idea how a light mover will do, it may be the answer, but if you are going to spend $500, don't settle for 70 watts of output. The Kessils are awesome, but they have no competition, which may play into the high cost of their technology and product. The technology is there. As for CFL's, which will work just fine for side lighting, but consider that LEDs last longer, put out more usable light in a focused direction, and offer UV for some extra crust, plus little heat output which may be an issue in a tent. If you are just looking for side lighting, get CFL, if you are looking to hook up your grow tent, check out your LED options. Like I said, check out Blackstar LED along with Ledgrowlightsdirect.com, Haight solid state, and such. Haight and Kessil are over kill for supplemental lighting IMHO, but they are really cool.
Shameless self promotion: If you want to see a newb grow with a supplemental LED check out my grow (almost 4 weeks in flower). If you like what you see: jump on an LED...If you don't like it: I wasted 500 bucks on an LED light.
Just to preempt LED haters: I am not a sales person, spokesman, marketing representative, or affiliated in any way to any brand, technology, or anything, I just like what I bought, and want to help others as members on this forum helped me. And I actually have a grow albeit my first.