Richard, I L-O-V-E my Marathons. Last summer I biked 2700 km (1680 miles) through eastern Germany, Czech republic etc with them...

NOT A SINGLE FLAT!!!

And then I hit - by mistake but I couldn't turn around - some of the worst "roads" I've biked on in my whole life. My bike was literally thrown between the stones, and it was constantly packed with four panniers.