I will throw the rugged obsidian45 in here, too. I have an octane, but in the k configuration the obsidian is an inch shorter and looks/feels/handles nicer on my reverse stretch.
I have 3-lug mounts for the RS, and pistons for the hk45t and p30. The interchangability between sico/rugged is a plus, but I prefer the rugged pistons and mounts.
Thank you, gents, for all the great advice and observations. Much to consider. I'm persuaded not to try to get a "one size fits all" can to use on both the SP5K and on my handguns. I'm aware that suppressing 9mm, particularly if you are not shooting subsonic 9 is not as dramatic an experience as we are led to believe. On the other hand, suppressed 45ACP is sure pretty sweet. I was with a guy who had a pre-ban/original/authentic MP5 and was shooting it suppressed,with the Knights Can and subsonic ammo. It was absolutely remarkable. We were shooting against static paper torso targets on large Kyvex backing and we could hear the suppressed shot and the loudest noise was of the rounds slapping the Kydex. Very cool. Ditto for steel.
I am a huge fan of the DeadAir products. Their Ghost-M is an awesome can. Mike Pappas rocks and his boys are rocking it.
Being fortunate to own eight cans, I'd like to reinforce the notion of "for best suppression get the suppressor best suited to the specific application". I've been down the ".45 will fit all pistol calibers applications" road. Can most .45 pistol suppressors be adapted to 9mm, .40 S&W, 10mm, 300 BLK OUT subsonic and .45? Yes, but all things being equal, a .45 can on a .45 handgun and a 9mm can on a 9mm handgun using subsonic ammo, the .45 can combination will never be as quiet. Why, because the hole in the end of the .45 is bigger than the hole in the end than the 9mm can. So with a bigger hole, the sound has an easier time getting out of a .45 can than a 9mm can.
My opinion of the ".45 will fit all pistol calibers applications" is based on the fact that a .45 can must have a bigger hole in the end of the can of the 9mm. Can a given 9mm can sound louder a particular .45 can? Of course that is possible. I stated above that "all things being equal". That would be two cans built using the same technology, the smaller muzzle opening would tend to be quieter. It is simple physics. There is such a very big difference in the possible technology in any given 9mm and .45 cans, it is possible to have a .45 can quieter than a 9mm. But if you love all the calibers listed above through your .45 can, good for you.
I tend to agree with Scott on the point that sound recordings do not accurately match the sound experienced in person. Somewhere on here I posted video comparisons on my Raptor 9 mm and MK9K 9 mm cans on my MP5K, both with sub-sonic ammunition. The videos don't 'sound' that much different but, in person, there was a definite difference, mainly in tone. Best I could describe it the Raptor had a bit of a 'crack' sound while the MK9K was a bit more of a 'thud'. I believe that the high frequency crack is more 'loud' than a thud. Maybe due to the difference in volume? If so, it would be neat to compare the MK9K to the much smaller Omega 9. Alas I currently have 8 cans with 4 more in jail but none is a Omega 9...
To the OP - there is a reason the modular cans are popular now, but also realize they are very new. It used to be "common knowledge" that extra silencer parts were verboten, whether baffles or end caps. Now all of the sudden you can buy 9mm end caps for your 45 can and have an extra tube/baffles laying around.
The 9mm end cap and the modular 45 can are really the best of both worlds. And I can't be crazy as Griffin, AAC, Dead Air, Rugged, SilencerCo, and even a new one called KGMade are making modular suppressors of some flavor. If you are going to suppress the pistols then Obsidian or Ghost seem like the 2 best choices. AAC Tirant 45M is out there as well.
I have an Obsidian incoming but I wouldn't be bummed to have an Omega 9K. I use ear plugs so the few db's here or there don't matter. I do want something that does not feel like an anchor on the end of my carbine/sub/pistol.