I struggled off/on with BiaB (mostly off) until I find got a handle on combining styles. The first version I had was V9, way back when. It is a bit disappointing to see the same clunky interface after all these years, BUT, this might be a clue to their survival. From what I've seen, they have a single developer. When new versions are released they are quite generous with counting up "new features". Point is that they aren't making anywhere near the investment in ongoing dev work that the modern DAWs-writers are.
My only experience with Jammer was the version included with PA8 or 9. Might've been a trial. Whatever it was it constantly crashed. In fact, my Jammer experience led me to BiaB.
As far as it being a toy goes, I guess that depends on how you use it. It is fun to play with once in a while, but IMO, it is a very serious tool for songwriting. Even if you never export or render anything out of it, BiaB makes it pretty easy to explore ideas that can be further developed by traditional means.