I'm running my Sherpa on 26 x 2 Marathon Supremes and find them almost perfect, they have excellent grip on wet and dry tarmac and are very comfortable easily ironing out the irregularities on the potholed local lanes. I find they roll very well and certainly find them quick enough for my needs. After using these I don't think I would want to go down to narrower tyres, I like the comfort these afford.
The only time I find the Supremes less than ideal is on loose, dry gravel, then the ride can become a little more interesting, but with a little care they still get me safely to my destination.
Adrian