The Hasselblad prisms don't interfere with most backs. So far as I know there are no interference problems with any of the 45 degree prisms, only some of the 90s with some polaroid backs, as I recall.

The one you've linked to works nicely, I had one with my first Hasselblad. It's a little less compact than the newer style prisms, but also much less expensive. You will be able to focus better, The view will be about the same or slightly less magnified than a WLF with the magnifier in place. But it also excludes the extraneous light which will also give you a better image.