I think this is the one I'll end up with. I like the mb feature on my harvester and the Scythe is checking all the boxes for me. Everyone seems to think the tbac5 just doesn't suppress enough to warrant it.
I have a TBAC 5, 7, & Dominus-K SR.
I can tell you that the 5 does tone down the sound significantly,, so characterizing it as "Not enough to warrant" is not accurate in my opinion. The U5 has a purpose, with all the accompanying sacrifices that come with the compromises found in any engineering design. The U5 is light (~8oz with mount), short (~4.5 inches over barrel length with DT or brake), and small in diameter (1.5"). It also shows not deterioration of accuracy, and has great sound suppression for its size and weight. If those specifications are what you are looking for, as I was when I bought it to fit under the handguard of my 300BO pistol, then it is unmatched as far as I know.
I recently ran the U5 on a 10.3" AR in a 3-day carbine class. I was grateful for the sound suppression, and the fact I only had 8oz extra at the end of my barrel when I had to go from low ready about 400 times. Don't believe the U5 provided some sound relief? Let me take the suppressor off and demonstrate a round without it, that will change your mind. Now I could have gotten more sound suppression by sacrificing weight and length, but the U5 is a compromise, one that made sense in this specific application.
The real question for you is what are you really after, and what is important. You started this with the idea that overall length was paramount in your choice. But now, you are drifting to a point that sound level is important. You also have not told us what cartridge/barrel length you are running, is this a gas or bolt gun, etc. These details matter. It is tough to get solid advice when you don't clearly define what you have, and exactly what you are seeking.
If length is most important, then the U5 is going to be hard to beat. If length/weight/diameter/accuracy matter, I don't know if there is anything on the market that touches it.
If length matters a lot, sound suppression matters a lot, and diameter doesn't matter, then you might want to look at the Dominus-K SR. It is about an inch longer installed than the U5, but has far more volume via a larger diameter. It is much quieter than the U5, though not quite as quiet as the U7. And the secondary retention may be a plus for you considering your application, i.e. going in and out of a scabbard. It is also still very light (under 12oz for both can & mount) compared to the market.
Then, as mentioned above, there is the standard Dominus and Dominus SR. Compared to the U7, the Dominus trades a larger diameter (1.8" vs 1.5") for a shorter overall length (6.25" for non-SR) to maintain volume. I don't have one for an actual comparison, so I have no direct feedback on the suppression of a full-length Dominus. But I see claims that it is at least as quiet as the U7, and has secondary retention with the SR model.
FWIW: I have no other suppressors besides TBAC. I am in no way trying to compare them to anything else, as I have no direct experience to warrant a comparison on my part. I will leave that to those that do have actual comparison knowledge.
