I have what would probably be considered a center console RIB, except that, like Stoo, I tried to design the floorplan for diving.
As such, I pushed the pilot's bench back against the transom. My boat is about 18' or so, with seating for 4. The pilots bench sits 2 (3 if one is my dive buddy's kid, who's 2 and a half), and a seat on the front of the console sits 2 more. Anyone else stands, hanging onto the radar arch, or sits on the tubes.
The boat, overall, *may* be a bit tail-heavy, but for the most part it's unnoticeable. If loaded really heavy, I'll have bodies move forward to help get on plane.
Bottom line is that balance and weighting and such seems to be more of a "what works for you" kind of thing.