I have no problems with coralife units, nor do I think that the unit is a poor choice (within the realm of UV units) for your type of tank.
As far as faith goes... when I started out in saltwater, I "concluded" that they were a miracle cure. I actually own at least 4 UV units... one Lifegard 40w, two Lifegard 25w, and one Coralife 18w or 20w, but they are all in the storage closet.
The position I have developed over a years of using them is that any benefit that they provide does not justify the expense of purchase or maintainance. The lamps are freaky expensive and have to be replaced frequently... twice a year or so, and the quartz sleeve inside also needs periodic replacement. They don't really do much for you IMO. Good husbandry and stocking practices can do ten times what a UV unit can, and these things are free. The other thing is that most people don't hook them up properly. They need very low flow... about 5gph per watt. Most people (me included at first), plumb them into a canister or return line which is way too much flow, causing them to do nothing but heat the water and cost money.
Now then, I also feel that expense aside, they don't do much "harm." I'm not a believer in the idea that they kill beneficial bacteria in significant quantities, so if you want to use one, I doubt it'll hurt anything. However, if you want a gadget for your tank and have money for a UV unit, consider a calcium reactor or an upgraded skimmer instead. In these two cases, you'll get a whole lot more usefulness for your money.
I do recommend them wholeheartedly for quarantine tanks.
