I’m using an old Mares mr12 III from the 80’s. Love it. Bought it used on ebay with a Dacor octopus. Checked it out on a tank, then a shallow spring dive on the Waccissa River. This was a couple of years ago. Slightly heavy breathing on both, so had both serviced. Been working perfect the last two years. BTW, don’t know how long it had laid up, but when I took it in for service, they checked it and said I could still dive with it fine, if I wanted to put the service off awhile. Had them go ahead, and watched while they did it. Clean as a whistle inside, looks and works perfect since then. I know a lot of folks say don’t buy off ebay, but I’ve got $165 in the regs and 1st stage, including the servicing two years ago. Won’t have it serviced until I detect a change.