When using the RF back you get all of the LF flexibility. You give up some quality in the lenses, though, depending on what MF lenses you are using. Someone here can correct me, but I am pretty sure that (for the most part) with each step up in format you lose some resolving power in the lens. While using the larger film area more than makes up for this when enlargements come into play, when you use a RF back, you are still in 120 size film. This isn't to say you cannot make magnificent prints from a RF back, that isn't the case. Just being technical :-)