Few more questions:
1. What is the difference between the Acute Matte and Acute Matte D?
My main reason for wanting the 501cm is that I believe they come with a better screen. The 501cm has a gliding mirror and some smaller ergonomic differences but a 500cm with an acute matte screen might be cost saving (I'm not entirely sure but that is my intution).
2. The longest lens that I would possibly consider is the 180mm. Would the vignetting be bad? I'm not a fan of telephotos in general, especially long ones. Realistically, I'd probably get a 120mm -150mm if I wanted a tele, which I may never get.