i'm on 700x28 marathon plus and they are a nice thick tire, with excellent flat protection. on my very glassy route i used to flat out twice a week and i haven't had one puncture flat since i put on the marathons. I just check them out in bright light every few days and use a screwdriver to dig out the shards of glass I've picked up.

HOWEVER, that said, if I had to do it over I would probably have just got the Marathon (non-plus) because of the weight and added rolling resistance. The difference is very noticable and if they deflate even slightly from the rated 100PSI it's like rolling through molasses.

Counter to what other posters have said, to me they seem to ride 'wider' than the rating, because the thickness of the tread seems to cause it to flatten out at the contact patch rather than being 'pointy' like my non-reinforced tires.