Here's my take:
I've grown with CFLs and always noticed the quality but never the weight. Then I met a guy who used HPS, and saw the weight, but not so much the quality. I've grown outdoor and seen both together, and, in my mind, it has to do with a complete spectrum being available to the plant. My latest grow, with CMH, turned out extremely packed with frost and really really greasy, but not so much weight. I've never seen a greasy bud till now, my neoprene gloves are slick and shiny with it. I believe its from the awesome spectrum that these CMH kick out.
I've seen some really awesome grows and I believe the key is to use a combo of light techs. We've seen the success from HPS/MH and I've personally seen awesome results from fluoro and HPS together.
I think that providing the plant with full spectrum is really the driving force behind quality buds. I know that CFLs and fluoros kick out UV light more so, iirc, than HPS. Also, the numbers I posted previously are for my 315w CMH 4200K lamps.
I do believe that UV light has an effect on bud quality. I don't have any sources to support that at this time, haven't looked to be honest. This is all my experience and conclusion thereof.