Here is a point that I don't think anyone has brought up yet. It may or may not be of importance/interest to an individual user.
Some manufacturers will void their warranty and absolve themselves of any liability if an octo or primary first stage from another manufacturer is attached to their equipment. It's usually in the fine print.
Also, with an Atomic regulator you can have either an authorized dealer service the regulator or you can send it to Atomic. Scubapro will not service regulators directly, expecting the individual to use an authorized dealer.
Prior to becoming certified on a particular brand regulator, we sent them off to an organization that used to charge $50 to service an entire reg set. The only part they would charge you for was a high pressure seat, usually $20 or so whether it needed it or not. They did give you an elaborate form with your intermediate pressure though. I would be very surprised in any organization can provide service kits and labor for a first stage, primary second, and octo and still make money at that price. Sometimes when its too good to be true its not.