Vectorspace? Anyone else?

I am driving from L.A. to Aztec, NM.

I've always taken 40 E from Flagstaff and then headed north on 491 at Gallup straight up to the Aztec area (two sides of a right angle with the points being Flagstaff, Gallup and Aztec).

Waze cuts a diagonal from Flagstaff to Aztec (avoiding Gallup), which is shorter and faster, at least in theory, by using 89 N, 160 E and 64 E, and then picking up the 491 at Shiprock.

BUT, I want to be sure 89N, 160E and 64E are all good, four-lane highways. I could easily add hours to my drive if they are 2-lanes that go through towns with reduced speeds and/or if I get stuck behind a slow vehicle with nowhere to pass.

So, as much as I love WAZE, I would appreciate some real life experience.

Thanks!