I tried to post this last night, but for whatever reason it didn't go through.
What fishon71 is referring to is the "piston slap" knocking sound that made news a few years ago. As best I can tell, only a relative handful of engines in pickups and Suburbans had the problem, and I believe it was traced to a problem with a batch of poorly-made piston rings from one of GM's suppliers, but I'll have to check into that.
A little more background: To the best of my knowledge, GM built two different variations of the 8.1L engine; a light-duty one for the pickups and Suburbans, and a heavier-duty one for the medium/heavy-duty chassis. One of my Chevrolet mechanic buddies told me that the heavy-duty version used different pistons, piston rings, valves and other assorted parts, although right off the bat, he couldn't give me a complete list.
I did some checking, and indeed there were at least two different RPO codes for 8.1 engines in any given year (there may have been more in some years, but my information was limited). This would lend some credence to what he told me, as GM doesn't simply create a different RPO for identical engines, there have to be some differences in order to necessitate that.
Long story short: Like you, Don and Gary, I've never, ever heard of a problem of any kind with the 8.1 in a motorhome.