If being Belfast based is your most important criterion (and FWIW I think you're very sensible to put home life first) surely there's no decision to make? BHD is also the happiest 'family-est' base that I've experienced on the network, as it happens. A good bunch, IMHO. There are some lovely parts of NI and property is cheaper than the mainland. Don't take your GB registered car, though if you're staying - you'll never get an MOT!! (honest).
Don't hang around,though: the recruiting boom can't last forever and, with 3 months' notice, it'll be spring before you can say "Whoops, crewing have shafted me again!".
Do it.