I have the Hybrid, the Vers 458 and the Vers 50. The Vers 458 sounds better than the other two, to my ears, with 458 SOCOM and 450 Bushmaster. I am finishing up a build in 45 Raptor, so that will be next. The only reason to buy the Vers 50 would be to mount it on a 50 Beowulf, which is what I bought it for. If you wanted that versatility, you can get the up graded stainless baffles on the Vers 50 for $150 more. The Bowers models don't feature a QD system like the ASR mounts for the Hybrid, and though there are many thread inserts for them, I don't think there is a piston system for use on a pistol, like there is for the Hybrid.
As for ratings, the only thing I have seen is that the Vers 458 is rated to a 45 caliber at 2650 fps and the Vers 50 is rated to 2200 fps, upgradable to 2650 fps. I don't know that Bowers has a barrel length limit.