Rolling resistance is identical to standard Marathons (using Schwalbe's own data tables). They are heavier, so harder to accelerate but easier to maintain speed. Grip is decent but unexceptional. Puncture resistance is unrivalled.
This really. I swapped to them from Continental All Condition Pro (26x1.0) so the difference in weight and hence acceleration was massive. But once you're riding they seem fine, rolling resistance not at all bad even though they're 1/2" fatter. helped by the increased inertia once you are moving I think, Grip and cornering also fine.
If you're only on the road, then the weight probably isn't worth it. But I've started riding on a bike path, and even though it's tarmac'd it's massively harder on the tyres than the road, the contis were shredding in a couple of months, whereas the M+ still look essentially brand new after 6.
