I have Marathon Plus 38c on a hybrid bike. Heavy, resistant but no flats.
I have Panaracer Pasela Tourgard with Kevlar on another bike 27" wheels 1.25" (which is about 32cm i think) and the riding experience is preferable to me, they have a nice responsive road feel.
So i am thinking to only use Marathon Plus when the absolute best flat protection is important, like if i was doing touring. For local riding, I would prefer something a little better feeling on the road (softer ride), like the Pasela Tourguard. For local commuting (12 miles one way) i am undecided which way to go. I havent been commuting yet. I decided that I NEVER want to use cheap tires with no flat protection on any rides again (ie the CST CZAR 25cm i got on a road bike. It isnt worth the lost time walking home and for tubes and the risk of a flat on way to work is too great. Ive never done touring but i would have to balance the added flat resistance of the Marathon Plus v. the risk and time lost changing flats with other tire models. Id have to try out bike setups fully loaded and see how more uncomfortable the Marathon Plus felt on the road in terms of "hardness" of ride and weight. Changing flats on fully loaded bikes might be a pain- taking a lot of eqpt off the bike, bad weather, etc.