I have a 25er and I had no issues with my Marathons, but even though there are more Marathons out there which could be why more issues are seen, I went with D rated Maxxis tires for my 25er. I thought long and hard about the E rated ones, but felt it was overkill since my weights are far, far less than the max rating of the combined D rated tires and a less harsh ride. I have now driven about 700 miles on them and they have performed to date, as well as I could have expected. I ordered mine right from Maxxis and they were only about 2 or 3 months old based on the tire codes.
JCanavera, who is very good about being on top of tire pressures and overall maint, had a tread peel off one of his Marathons after a long trip. For him, he was lucky, it peeled off as he was backing back into his driveway. He has a slide out, so for him to go to E rated tires made sense due to his extreme weight additions of the slide out.
Also, the Maxxis tires have a nylon cap. I don't think the Marathons do. If you do some research on the web about what nylon caps do for tires and tread seperation, I think you'll find the Maxxis to be a better tire, by that's just my opinion.
Computers manufactured by companies such as IBM, Compaq and millions of others are by far the most popular with about 70 million machines in use worldwide. Macintosh fans note that cockroaches are far more numerous than humans and that numbers alone do not denote a higher life form. -NY Times 11/91