MK 11 and 17 are pretty nice regs, service or not base on the IP gauge. The EVO regs are just the latest anti ice attempt, scubapro has been trying a lot of different things over the years to make unsealed pistons work better in the cold, I don’t know what if anything they did with the 17 to make it an EVO except some really pretty chrome and changing the HP port angle a little to make it harder to get at.