these bulbs are amazing.. there's many things great about these
-super great color ( 92 CRI index )
-amazing spectrum
-a lot of power in the red spectrum
now some things to keep in mind.
-these ballasts run hotter then a "normal" electronic ballast
-small wattage
-low support for bulbs
-mercury still
4x4, honestly, I can't suggest this for you, as it's just not the right setup. it's perfect in a 2.7x2.7 tent. 3x3 I think is pushing it a little, seen a grow but wasn't finished so can't say, but it could work, but don't expect the fattest buds.
the idea of running led with it is fine I guess, but it's so nice to not keep adjusting many lights, but just one ( the CDM ).
this product is pretty cheap at horticulturesource , and bulbs are cheap there.. but I would think the e papillon system would be a little better as you can replace the insert as they sell separate, and the open air design is better but it costs a lot more. but I have not got a chance to run one with my actual hands, but I have a couple of the sun system CDM, and a built one for a bell hood for a 2x2 tent ( can you say 1000+ PAR with me ) 1000+ PAR.
you can build one also, if you can find the parts cheap, it's cheap then these, but then it's "DIY"
also to keep in mind, there 2 versions of that system, 120 volt and 240. if you get 240 and only have 120, you need a voltage transformer from amazon or the likes.. just pointing that out if you buy one there is 2 models..
honestly I'm not sure why more people are jumping at these, I think it's the price, but i never care as what you grow is worth more then buying 100 fold..
if your wondering if they grow, go to IC, and check out the CMH sub section in the lighting, and go to the last 10 pages, and check the grows.. also a guy named rives, check his pics....