What's the full routing? A large portion of your trip is going to be in economy PHX-YUL (and maybe onwards if not going YUL-ATH).
But regardless of the routing the same is true for AA, so this doesn't really move the needle at all IMO.
On AA it would presumably be PHX-ORD/JFK/PHL/CLT-ATH or even PHX-LHR-ATH. The shortest AA connecting flight option (ORD) would only be about an hour shorter than going through YUL.
Not something I would spend $400 more for, but to each their own.