First off, I'm praying for your recovery; that's rough and I think you have your priorities right.
I asked about barrel length because your observance of basically (my words) "caked with carbon" and wall thickening in suppressors; I figured if guys are using suppressors they're probably using other NFA items (such as SBR's or even in your case MG's). Just referencing the picture of my wife with the 12.5'' SBR. I believe that the experience you have with predominantly SBR's (and MG's at that) in 5.56mm and longer barrels in .308 (I had a feeling you didn't shoot SBR 7.62; it's just not enjoyable) may have shaped your perspective on using non-dedicated suppressors. I think that the SBR and Short barrel MG's given how much unburnt powder (or still burning looking at the muzzle flash) may leave larger carbon, etc. deposits earlier on in the baffle stack of a suppressor than on a longer barrel (or potentially non FA).
In short, I think the full auto and short barrel may have caused the caking issue (my words) to be exacerbated (I believe either would but combined; I certainly think it may have).
I don't know that the OP would have a similar experience taking a .30 cal can across multiple platforms. But I'll also say this; your first hand experience with suppressors far far outweighs my own. Sure, I've spent a lot of time looking at them over the years and NFA items have been where my interests are primarily; I'll defer to your experience over mine.
One thing I'll add, unfortunately one other truth is... silencers are pretty much a disposable item; it's unfortunate but I truly think they are and especially so in silencers that can't be disassembled and cleaned (pretty much all heavy use rifle silencers). KAC indicates that they have rifle silencers still in service with over 50k rounds through them (Trey Knight at 13:00 on
https://www.youtube.com/watch?v=bE939qTSt8o). I would look for a high quality metal (inconel or now stellite at least for the first baffles; as I understand it Ti can take the abrasion but not the heat given to the blast baffles), fully welded core, and ideally a serialized portion that is replaceable in a rifle suppressor.
There's a company Stalking Rhino Inc. (
http://www.stalkingrhino.com/) may help you re-core, re-build, or improve some of your old silencers for no longer in business companies or discontinued silencers(
http://www.stalkingrhino.com/jailbreaking). It seems that the NFA market has created a unique niche for that small company and I've heard good things (I'm not affiliated in any way). They don't have re-builds pictured but I've heard good things about their results.
I see a purpose for silencers but where I am in life; the juice isn't worth the squeeze.
To the OP, I think you made a solid choice with the Rugged Surge, and you can change the length of the suppressor. I'm impressed with it.
God Bless,
Brandon