When you combine a Z fare with another fare, AC considers the conditions of your ticket as the most restrictive conditions that apply (eg Tango + with Z = T + conditions and mileage accrual). I found this out recently when I booked a T+ and Z combo. However, my AE account does show the extra 25% mileage for the Z legs. They may take that away at some point, but so far there they are.

Still, if you can push over the top for your mileage, I say go for it. I have enjoyed being E the last few years. There are the SSWUs, as well as in my case the useable SWUs as I had a London Pass last year, and then there are the occasional op-ups. I have had 4-5 of those so far this year, which isn't too bad, and I got one LHR-YYZ last year.