Dude...don't worry about that. A lot of growers have their own little suspicions or findings, but that doesn't mean you should believe every one of them (you'd go crazy, because they conflict half the time). It's pretty clear from many, many growers that HID lights (mh/hps) are the easiest way to get the best and biggest buds. I know people can get amazing bud from CFLs and other types...but HID is clearly the way to go if you have the money for it. It gives the most light, and the best type (mh during veg and hps during flower). You've made the right choice on lights. Just don't burn the plants and you will be more than fine (24"+ for seedlings, 12-24" after - use the hand test; if it burns your hand, it'll burn your plant). That being said, many people believe that UVB does help potency. If you wanna run out and go get some lights that provide UVB then go for it, but I'd try a grow without it first and see what you think.