Many BIBOA members are to be found on RIBnet.
Both are very much active and alive in different ways.
Unfortunatly, you are correct, BIBOA is generaly for the bigger boys toys and they prefer paper newsletters... as opposed to techno-RIBnet (which is free) where the small RIBS often seam to meet up for events geared more at the ability of a sub 5m boat.
Don't let the size thing put you off, i joined in some BIOBA stuff in my wee 18ft boat in the late 90's as did others in even smaller boats, Daniel II springs to mind with a 4.7m Tornado at the time i beleive.
They are a friendly enough bunch