I've had the MOPs for around 20,000 miles now and have learned a few things. If you keep your feet down on them they will scrape in anything more than a moderate turn. You learn to "feel" when your heel will begin to scrape and lift it so it doesn't. In more severe turns, you must either pick your foot up (not too comfortable), of go back to the foot pegs.
Knowing this, I wouldn't take off on a long trip without them. After you've put on a couple of hundred miles in the morning, it feels really good to be able to stretch your legs out without putting a great deal of weight on your tail bone (even more uncomfortable). I have the model that are curved and allow your feet to rest at a more natural position (not sure of the model number anymore). I know that Jim **** is working on a stronger spring so you can replace the open aluminum foot rests with something "more substantial", but I'm not sure if these would be more confortable or not. Maybe I'll try them if Jim is at Americade this year and has them ready by then.
Working with Jim is pure joy. He has always been supportive of our needs as GL1800 riders, and is just generally a fine Christian man. Its a pleasure doing business with him.