Well, I read on RC .... just kidding. But what I have to offer may not be all that more useful anyhow because it's based on what I've heard over the years, RC or whatever. But since it beats real work, I'm typing this in anyhow. The difference between NO and HO and VHO is the amperage the current is carried over (bear in mind I am not an electrician and am not trying to be, so for you electricians out there getting a facial tick reading my statement, sorry about the facial tick, go get a coffee or something
). And anyhow, a Fulham ballast, I thought did output at the VHO amperage whereas the Icecap ballast outputs more at the HO amperage. I know that there are all kinds of other differences like frequencies and whatnot, but that is what I would guess is something to do with the T5's lasting longer. Icecap's claim to fame all along has been that lamps last longer on their ballasts (halides or fluorescents) and it seems to me that they generally seem to acheive this by underdriving lamps, but tweaking things like frequencies so that the output lux are "close enough."