Bird said it all...but in my circumstances, I prefer the loader on. I can't raise the cutter without making the steering to light for my tastes. I'm sure my property is more sloped then Bird's though.
Anyway...my reply actually deals with a recommendation. At least give a good look at the 5' Land Pride cutters. They're extremely robust (as long as you don't mind the sheet metal getting dinged up). I've cut some thick tall stuff of all sorts. My philosophy has always been, if I can push it over, I can cut it.