I've been using Dacor regs since 1986. I've always been treated very well by Dacor and its retail agents, particularly when Mares took over Dacor and scrapped all the old models.
Dacor regs are built by Mares so I don't think quality will be an issue (not that it ever was).
I currently have an Eagle DPD Pro with Eagle Octopus. I wish I'd thought about getting the Viper Octopus because as has been previously reported, there is no right way up with the side-exhaust.
I really like the turret on the first stage for the primary reg hose - allows a lot more freedom and prevents me from feeling as though my reg is just about to be yanked from my mouth. This system is also available on some Viper regs.
People have expressed concerns about the strength of the turret, but I have never experienced any problems. Dacor have proven this technology, my old XLE 960 also had a turret first stage.
Re the Viper, some reviews have said that they find it very hard to use the purge button with gloves on because it is quite small.
All Dacor regs are cold-water rated but it you're going really cold below 10c go for Viper metal with the heat sinks that help prevent icing.
Hope this helps and safe diving.