Don't think there's anything in the stable repo yet (the stable repo actually doesn't exist yet). That said, the build in the latest repo (24.0.28) has been pretty stable for me, but your mileage may vary depending on what Linux distro you're using. IMO though, adding a MC24 for Linux build to the stable repo should wait until after the internal browser stuff fully lands (and is pretty stable without issues, like it not working on Ubuntu 18.04). Mainly I think this because of the registration changes that occurred in both 24.0.26 and 24.0.32 beta (which require re-entering the license key again) so to avoid having to re-enter the license key twice in a row.
It's worth pointing out that MC for Linux and Mac are different than MC for Windows (the main JRiver platform, IMO), which is more-or-less pretty stable now. MC24 for Mac (24.0.25) is actually pretty stable too, in my own experience.