I recommend using the Hasselblad screens, the acute matte D are the best (they are the most expensive for a reason).
I've used several aftermarket screens that were quite good (Brightscreen, Arax, no-name Asian) and some that were not (Bos, Beattie). The Brightscreen was the best of the bunch I tried, and worked well with most of my lenses, but when I got the 110mm f/2, I found that it back-focused all my images (and in retrospect, the other lenses were slightly back focused with that screen too, just less noticeable within the DoF). All the Hasselblad screens were bang on with the 110mm. So I just use the acute matte's now.
This is not to say that all aftermarket screens are out of spec, but the genuine Hasselblad screens are good and consistent.