Grasshoppers would be my choice for heavy mowing, I retired in 2011 and was driving my wife crazy, my son was the lead grounds keeper at the local Golf Course and with a few choice words from my loving wife he asked if I wanted to mow 3 days a week. I did and it ended up being full time in a couple weeks. I mowed the ruff, about 60 acres, every week, now that was at 3" took about 20 hours a week. The mowers were the Grasshoppers 329 2009 models 6' decks. Kabota 3 cyl gas. The only problem with them were the deck spindle bearings, rebuilt every year, new bearings and seals. The upper bearing was the failure point, The upper bearing even with constant greasing the grease would drop out of the upper bearing. After finding the problem I changed the upper bearing to a sealed one side bearing with the seal on the lower side so the grease would not drop out of the bearing, The new upgrade let the bearings last over 3 years. I worked there until I was 75 and loved it, money wasn't great but I enjoyed every day.