I run standard Marathons (the 1.5 inch, 100 psi ones) on my Downtube Full Suspension (and on a couple of other bikes), and they're great, pretty flat resistant, long lasting etc. I've got Supremes, however, on the old tourer that's my regular London commuter, and I have not had a single flat since I put them on over a year ago, despite terrible road surfaces and clumsy early morning riding. Strongly recommended.

It's only my 3rd day commuting with the new standard Marathons, and they're much more stiff and responsive to my stock Kendas that came with my Downtube full suspension.

since you own both tires, how are they different in terms of riding quality, speed, tire grip? I'm asking because of the huge price gap.

Riding quality, tire grip, I'm not really aware of any difference. Noticeably faster on the Supremes though, which I suspect is a combination of weight and rolling resistance. Worth the difference just for the puncture resistance though; I am a large, heavy man, and I just can't seem to puncture the Supremes. Diana Ross on her own, maybe......

thank you very much