I used 2.0" folding bead Supremes for a loaded tour through France and Spain in 2011. Mostly tarmac and reasonably good cyclepaths, but some rougher bits.
Very light for such a wide tyre, and roll very well. I did wonder whether they would resist rough tracks with a month's load of luggage (all up weight was between 109 and 123 Kg depending on food stocks and rider's fat level, the later dropped during the tour). In the event the Supremes held up fine, just as well because I decided to risk it and not take a spare, reasoning that in civilised Europe I could probably get a 26" tyre fairly easily if necessary.
For off-road use, obviously not as much grip as a proper MTB tyre or even something like a Dureme. The Supreme's sidewalls are thin so probably more risk of failure if you hit a sharp rock.
So far, good puncture resistance and good durability - the moulding in the centre of the tread on the front tyre is still visible after 7,000 kms. And not too expensive at 32 euros from my local bike shop.
Dureme is a bit heavier, in my opinion slightly slower, but better protection on the sidewalls.
Subjective, but I reckon the 2.0 Supremes roll better than the 1.65 Marathons I have on my old commuter bike. The Supreme is certainly lighter at 565 g compared to 820 g. I'd rather go for a fat but light tyre rather than reduce the section to try and save weight.
For a more demanding tour, I would be tempted to keep the Supremes, but carry a spare just in case.
