You should be coming up soon. My Hydro-S 7.62 was 5/17, and it got approved on 2/10. I just started the process on this one so I'm a little over 30 days in on this one. It'll be a while...
Dude, I know Jay said it has a lot of back pressure, but honestly, mine isn't anymore gassy than either of my Sandman-S cans on that rifle... Brass still ejects at 3 o'clock (same as my SMS), still the same amount of gas in your face (inside the building with no wind) as my SMS if I run it hard, and behind the gun, it sounds about the same DB volume as my SMS... BUT... It is significantly quieter as a bystander. There's a huge difference between them from 5+ feet away from the shooter...Which is where that muzzle DB reduction numbers really come into play...And downrange volume, as well.
Honestly, for $550, it's a no-brainer. It's easily the best duty-rated 5.56 can I've ever shot. It stomps the YHM cans i've heard hands-down, and everything else in that price range by a wide margin. I haven't shot a Sierra5 yet, so I can't compare it to that...But I am interested in trying a Sierra5 someday.
My thoughts are... If you don't have any/many suppressors and want something kind of universal, but hardcore/duty rated, for many different guns/calibers, then go with the Sandman-S or Nomad-30. But, if you DO want something that is dedicated for 5.56/6mm rifles, then without question, get a Polonium.