The guild was set up as a place where everyone, no matter what their playstyle, or time available for playing, would be welcome. This is true today as it ever was.
Although from what you say about your position the progression raid teams would not suit you there will be lots of other opportunities to not only raid but also to take part in any of the other guild activities.
I would say give it a try. You have nothing to lose by either transferring a couple of toons across to SWC or even starting a fresh one.
There are lots of us in the guild that have tons of alts. We now even have an associated guild to put them into. And someone with the experience of multi-boxing 5 at a time would be very welcome. I have trouble dual boxing and I wouldn't even think of taking them both into the same instance