CMC-2 are AT831, right? (There is also a CMC-2A, which I believe is different, though I have not seen it.)
If so, I wouldn't expect much difference between these and CMC-8, aka AT943 or AT933. So no real need to upgrade.
Note that if you want, you can put regular AT853/U853 capsules on those AT831 bodies. The capsules stick out a bit, but the threads are the same, and they work just fine.
So, just stick with the AT831, and maybe try a few other capsules if you feel like it. The subcards are recommended by several people here.
Richard