This has been fun to watch. The ENTIRE sealed vs. unsealed piston debate in one thread, plus a seat-saver debate on top of it!
Let's summarize. There wasn't a huge price difference. Two TOP manufacturers!
It really came down to what has always been the case... unsealed Scubapro wins because of a worldwide service network and the cost (and mess) of sealing an Atomic. Techs don't love them, and rarely seal them right.
So here's the deal. If you provide average maintenance rinsing after dive trips, your reg will last 25 years. If you're really diligent, it'll last 40+. But you may have stopped diving. Atomic, on the other hand, might last forever.
But if you don't provide good rinsing, you'll have to replace the IP cap, which Scubapro will probably still stock 15 years from now.
But the S620Ti second stage? Ah!
You'll have had to service it at least every two years, and may have had the knob assembly in for additional service in between, when it froze up.
If you wanted it tuned light, it'll have freeflowed at least once about three months after service due to seat indentation. If you didn't care how hard you had to suck (or didn't know), you never knew the difference. The Atomic seat, on the other hand, wouldn't have turned a hair. But then, you'd have had to take a little more care during rinsing (which DOESN'T include having a tank and rinsing while pressurized).
It's a simple as this: if you're a regulator geek, you'll go nuts with the obligations of Scubapro service. You'll tolerate the hassle of sealing the Atomic, but love the interval and consistency.
Potatoe...potahto.
Me? I won't dive a Mk25 because I can feel the scrape of floaty grit inside the piston land every time I take a breath.
Okay. Not really. But I hate unsealed pistons, bwaahaha!
You did fine. Whatever you chose.
Just find a GOOD shop!
Scubapro used to seal their pistons (think SPEC Mk10). But complaining techs killed it. And here we are...