when it comes to B4 vs RSB, it's personal preference.
When choosing mine, I could have gone either way, but I really didn't like my dads BH. things like the steering was too light, car's to heavy etc. Some prefer the refinement however, and they really do feel like limousines sometimes. Great for cruising. If i had to go through it all over again, i would still chose a Gen-II any day, without hesitation.
As for the rebuilt thing, may be a good idea. Sometimes it may be better to just look for one that has simply been un-touched (i.e, no ricer mods) and has a service history.