To be honest I don't think it's a bad thing that the existing society doesn't have a huge SW following. To me SW and FW are disparate enough that it really would be a headache trying to keep everyone happy. The different categories of FW alone actually have got to be a challenge.
To me it's a no brainer, there should be two societies but closely affiliated. Sort of like how in the plant world, there's the Calgary Horticultural Society and then things like Foothills Orchid Society or whatever. Each has their own meetings but one is like a "parent" to the other. People have to be members of both though, membership in one doesn't include full membership in another.
So I think a reef society could learn a lot from the folks at CAS.
Just my $0.02.