M and N have the same engine and nearly the same top speed (a few mph off for the N), but the main difference is the N has a higher dry weight. Even if you load it lighter on the gas it'll still be a bit heavier than the M. I don't recall if it's 500 or 1000 lbs, but something close to one or the other.
Overall, a light N will fly similar to a regular M, and overall they're both very lethal. Pilot error makes most of them fall into the same traps and pitfalls that the D models fall into, but they are a bit superior to their early brothers.
P.S. The N has squared tips, and slightly larger ailerons, but it also has longer wings as well, so the net result is that the roll rates are almost the same. No clear winner in that category, either way.