"Researchers" who never owned one......well I'm not drinking the same GM kook aid you are, but I have owned:
2015 1500 z71 crew 4wd 5.3/6sp
2012 Traverse 2wd (wife)
2010 1500 2wd crew LT 5.3/6sp
2010 2500hd crew 6.0
2005 2500hd crew duramax
2005 1500 ext cab z71
2001 1500 ext cab z71
2004 Tahoe 2wd LT
2-1998 4wd suburban 1500's 5.7/4sp (hunting rigs)
I've also owned my share of Ford and Dodge pickups since 1998 also, so I'm not some die hard supporter of any of them. The most problematic vehicles I've ever had were the '10 and '15 Chevy trucks listed above. Gm trucks and suv's in my opinion were better built and better driving in terms of engine and tranny on the pre 2010 models before they changed to the 6sp auto, and even better on the pre 2007 models that had no AFM.
I've not driven a 2015+ SUV that had any buffeting or "booming" that was enough to bother me personally. I have driven one that had a very noticeable vibration, a Tahoe, which acted exactly like the people here and elsewhere describe the vibration issues they have encountered. I've also had my fair share of quirky transmission/AFM issues on the '10 and '15 pickups listed above, so I do believe 100% that AFM is total junk and unnecessary given the extremely marginal benefits (if any) that it may provide. It sounds like you also believe that the 3.08 is not satisfactory unless the vehicle will never tow, as you said you re-geared your avalanche to 3.42. A 3.08 is great for the consumer that will ever ever haul more than groceries, and will never go up at all in tire size, but if left with a choice, I'd recommend anyone to a 3.42. My 3.42 pickup with a whopping total of 3000lbs behind it screamed and shifted like crazy on interstate drives in the southeast, so common sense says a 3.08 would be noticeably worse.
I had factory cloth in my 2010 pickup, which was total garbage, collected lint like it was designed to do just that and held in any strong smells that ever got into the truck (food, wet clothes). It was my first and last vehicle that left the dealership with cloth seats. Cloth by most manufacturers is more difficult to remove stains/spills than leather. As for long term durability of one vs other I haven't the slightest clue and don't plan to find out, because that would require me to run a truck with cloth seats for a while.