I know this is an older thread but I own two Exmark 48" Triton's. We cut Bermuda and Zoysia very little fescues. But often when the lawns are weedy and have taller stems such as the tall fescue variety, it will require us to double cut. Wet tall grass will cause my mulch kits to sing as if you have a stopped up nose in the choir. These decks are not stamped and have corners. The mulch baffles will hold grass clippings and will cause your so called mohawk appearance. If the blades can't cut the grass fast enough during the RPM cycle, then this tells me to slow down. Too fast on those hydro's to get stuff done.
Cleaning out the decks is a weekly, sometimes daily job. Heck even between some jobs it has to be done.