After three, yes three, sets of Open County AT 285's I'm 12K on M-55's. They're mounted on Weld Outbacks. No ride difference I can note, but they do sing which I would expect since the tread is much more aggressive.
AT's were quiet, good in rain, but they don't wear beyond 35K for me with 5K rotations and weekly pressure checks. I like the M-55's so far.