as with putting a color filter or lens on anything, it actually takes away from you than it does give you. any light that goes through glass, plastic, filters, artifical colors, etc will detract from what light is really being given off. So be careful with these lights.
Yes, you can flower with LED's however, in my last thread on my experiment, there are VERY ranging differences between lights, and there are some precautions (new ones) to watch out for. I have also placed an image from my camera that I took which shows the color patterns and how much penetration there is between the canopy of the plant. There isn't much at all, and this is where the trick of the LED vs. HPS comes in.
Roughly a 400w HPS puts off about 55,000 lumens, of course you can't get close to the plant with that due to heat, and the LED's might put off an equivalent lumens per watt ratio, however, the penetration is still just a matter of inches with the bulb right up against the plant (touching). So there still is work to be done. And in Alienbaits LED thread, he posted a spectral analysis chart for HPS, and LED and the proper spectral graph for flowering plants. HPS is within range but lacks in the aqua color range, where you'd have to tweak your LED color patterns all across the board... but I discovered that CFL 2700k have ALL the proper colors without having to tweak regardless.
graphs located here:
http://www.marijuanapassion.com/forum/showthread.php?t=18126&page=4
So to get back on point, a standard 2700k bulb without any filters, paints, colorings, is still your best bet.
I just built a flower setup for under $50 kinda similar to yours... well.. not really, but my supplemental lighting will be very close, using the same setup for under canopy growth
http://www.marijuanapassion.com/forum/showthread.php?t=20024