I didn't read the entire thread, so I'm sorry if I am repeating stuff that others have said.
-Nothing branded "redneck" or "shithouse" will ever be on one of our trailers.
-How about a machine that is set up for real attachments. Like snow-thrower/plow, rotating brush, blower, aerator, etc? Like a Walker, but not slow.
-The detachable fuel tank idea is cool, but I take the truck and trailer fully loaded to the gas station, and just fill everything for the week (truck, mowers, and two 5 gal containers). I am not sure how detaching would help.
-My next mower will probably be a diesel. And it will go 13mph minimum.
-Around here, we need a nice vac/collection system like on an Exmark. Bigger capacity is better. But QDS is useless for us.
-No flat tires. Tires are the biggest cause of lost productivity.
-Easy grease points, and oil/filter access.
That's all I got.