Our experience has been that WM's chicken is about one pound lighter. I have seen some that almost look like quail.
I am certain you are right, but for 2 senior adults, WM chix is already too big, and none of us are big fans of leftover chicken. I end up boiling the carcass in water and it makes decent chicken broth for future cooking.
Smart and Final also has those HUGE rotisserie chickens and Smart and Final is a lot easier to get in and out of!!!