Have used these tires for a bit over two years now, and find them satisfactory for most conditions. I run them at close to 80psi most of the time, and down to 60psi on rough trails. Not a pure mountain bike tire by any means, but can take on most gravel, dry dirt, grass and small rocks with ease. Gets a bit squirrelly in wet conditions and larger rock. Runs very smoothly on dry roads. I am very confident on these tires as the tread and construction appear very solid and puncture resistant. Only reason I would change tires would be to go more aggressive for off-road wet and large rock conditions.
I previously used the conti 4000's and converted to these for my go to race tires for the past two years. This with a latex tube is a wonderful smooth ride and extremely fast. I've had my best bike splits in IM distance and HIM distance races.
I like the 4000 S II 700C tires well enough that they're the only ones I buy. I bought two on sale at half price to keep in reserve for when the others wear out-eventually. The price was too good to pass up on tires I prefer.