I doubt durability is an issue here. I've had my current horn for several years and it took a hard fall a while back. The fall was hard enough to bend the bell (inside the hard case) and I think stressed 2 things attached to the bell - the leadpipe and the brace near the bottom of the bell. The slides had to be re-aligned because of this stress, but the AGR/leadpipe are just fine.
The AGR outer piece is quite heavy and very solidly attached, probably at least as well as a standard receiver would be. The turning barrel is secured with this rather tightly and is finally tightened with the thumb screw. The AGR is threaded to a reinforced leadpipe end over a fairly long threaded piece, so it also should be mechanically secure.
My horn is not as heavy or as heavily braced as the old Bessons, for one example. So it won't take a hit as well. But if it were as heavy as the old Bessons it would not play as well. But in my book, the AGR is not a worry. The only vulnerability I think it adds is from lack of maintenance. If there threads are not lubed now and then (not very often is OK in my experience), I suppose they could get locked up. If that happens, an amateur trying to loosen them could warp the leadpipe. I probably only think that because of a junior high school experience. The janitor knocked my horn off a chair when I was out of the practice room. It didn't really hurt the horn, except that it jammed the mouthpiece into the receiver. He applied his locking pliers to the mp and got it out, but twisted the leadpipe in the process!
That last anecdote, by the way, is why it is nice to support having music stores nearby. They often a repair tech, and this fix was no challenge for the tech at my local music store in Davenport.