Here's a good review and followup commentary from Graham Smith on crazyguy: https://www.crazyguyonabike.com/reviews/board/message/?o=Sh&thread_id=350687&page=1&nested=0&v=2i
I included my own experience with these tires with some posts towards the end of that thread. Just did a quick search on the Thorn Forum for 'Schwalbe Marathon Supremes' and that turned up several threads here as well.
My quick résumé of reading/listening/experience would be: lovely tires, vulnerable sidewalls, be prepared. WRT being prepared, I found some HD sidewall repair patches made by Filzer, which I'll add to my kit. A post by Rual on one of the Thorn thread, which I've been unable to find, included a tidy bodge (my word, not his) for a cut Supreme sidewall which uses fabric medical tape, Elastoplast or something similar, stitched into place with dental floss. This has a repurposing elegance that makes me almost long for another roadside problem, just to try it out -- or maybe not, maybe I'll just try it on one of the disabled/repaired Supremes in my workshop.
Worth noting, finally, that a fair bit of the commentary on Supremes describes experience with the 2.0" variant. Not sure if these assessments differ significantly from those for the 1.6's, aside from the fact of lower tire pressures. The question of appropriate pressures for the 1.6's has a wide range of answers, from "on the low side of the recommended range" to "maximum". This coming summer, on tarmac I'll use 60-65 psi front (~65 loaded), and 65-plus at the rear, ~70 when loaded; a bit less on gravel.
