I’m not surprised the roll-off design is so popular. Incredibly adaptable.
So far my “many small wheels” design has held up although I’ll probably go with larger wheels as you suggest when a refit becomes necessary.
The lightweight covering has held up after a dozen storms and it’s still completely dry. I think I’ll put another layer over the top before winter just in case. An entire covering only weights a couple of pounds.
The only issue has been with a slight sag of an inch or so, in the actual roof front due to the natural ‘give’ in the timber. Once the roof rolls off there’s minimal support at that point. I have a 2.5m 2″ x 2″ angle iron lintel which should cure it buts its minor.