cold salt water? not a prayer of getting me into an unsealed piston reg. Too much of a PITA. Are you bound to Scubapro for any reason? The reason being is that the MK25 offers the best hose routing of any style of reg out there, 5 port swivel turret, for backmount singles and doubles, and sidemount. That said, a sealed diaphragm is best for that, and the Dive Rite XT would get my nod for a new reg at the moment. The Deep6 regs should be here in a week or two and will be a great option, but you won't be able to get them serviced, you'll have to do them yourself. Dive Rite XT's are best of all worlds