Jamba 0.5 available for testing (Update 12).

[Jafula]

I like the merchant repair and selling gray items of Jamba better than other addons I've tried.
Would it work to just enable those two wow addons for my non-multi box characters?

Yes, they should work just fine. They need the core Jamba addon, but apart from that, have a team of one and you should be good to go. Just enable JambaDev, JambaDev-Sell and JambaDev-Toon and disable the rest.