The NDG section of the de Maisonneuve path has been terrible for the past 10 years at the very least. The last time I took my road bike on it was over 15 years ago. I've only been using my hybrid on it for getting into downtown or an occasional training run. The entire street needs to be dug up and rebuilt from scratch.
In the past, I would take Sherbrooke instead, which is actually more appealing now since it was recently re-surfaced. But I'm still using the path because of less traffic lights through NDG-Westmount. I wouldn't call it a Valley of Death, but you can forget about a peaceful ride.
Regarding the overpass, do you mean the intersection at Decarie? Compared to everything else, this section has never really bothered me. I believe the intersection will be re-modeled in time for the Super Hospital opening (we'll see if they even break ground on this one).