The main reason why I want to use the WLF is for focusability.
From my limited experience, it is much easier for me to focus MF SLRs using a WLF. The reduced weight and 100% coverage are additional bonuses. The inverted viewing is neigther a pro or a con for me. I prefer inverted viewing for deliberate shooting and noninverted viewing for quick shooting.
Actually, I see no benefit of using the Prism on this camera, except for maybe ergonomics...given that it is not a box camera. (not sure--I have no experience).
I have a Rolleiflex. The reason why I want this camera is for the 105/2.4 lens, mostly. I don't mind using a WLF because I seldom shoot portrait orientation and I like to be more deliberate (slower) with medium format.