Scubatooth once bubbled...
the reason you see alot mentioning of the apex on this board is because of the DIR and GUE guys because this is there general reg recommendation.
I disagree.
The reason you see a lot mentioning Apeks (not apex) on this board is because they're great, reliable, bombproof regulators that have excellent performance, cold water performance, hose routing, availability, features, and price point.
Those just happen to also be the reasons "the GUE guys" recommend them.
As for the Viper Metal, I don't like the sound of it. 5 LP and 2 HP ports? What on earth are you going to put on all those? I don't like side exhaust regulators for a variety of reasons, the first stage has a pivot, I don't think the first stage is sealed, and the second stage only comes apart with a screwdriver... and the diagrams on Dacor's site make the second stage look pretty complicated mechanically. IMO, simpler is better. Oh, and Divernet says the Viper Metal is noisy and the purge really sucks, requiring two hands to use (!). Here's a quote:
"I really wanted to like it because it looked excellent but I found that one eye was constantly obscured by exhaust bubbles. The flow of air from the purge seemed weak, although it was hard to push on to make work. Although the breathing was acceptably good, I'm afraid I was disappointed overall."
By comparison, here's a typical quote from Divernet of the [more inexpensive] Apeks ATX50:
"Just superb. The best of all of them. It proved extremely comfortable and it gave a superb delivery of air. This is the one I would choose to buy without any hesitation whatsoever."
This reg has a sealed 1st stage, comes apart very easily, is simple but obviously effective in design, doesn't have the annoying qualities of a side exhaust, breathes with the best of them, and doesn't have an a$$ ton of useless ports. Oh yeah, it's also cheaper. Go figure.