more work in GA than RAA will ever be
I find that hard to believe. There are RAAus schools popping up everywhere, and the GA schools seem to be going the other way.
And what exactly is your husband building hours up for, if he was going down the RAAus instructing route anyway?
The original poster sounds as if they just want to do it for fun, to keep their hand in so to speak.
I instructed RAAus and GA for a few years, and I clocked up a lot of hours very quickly. The bulk of it was ultralight though. I'd say the mix was about 70% ultralight instruction, compared to 30% GA instruction. It was a means to an end though, as my ultralight instructor rating got me my first GA instructing job.