Yes, you're correct, that deprecated APIs often break, but here is a big caveat, especially for OS APIs:
Deprecation in itself, doesn't warrant breakage or removal.
It normally means that you shouldn't use this API for new stuff. E.g. look at Carbon: It's long deprecated, but as of El Capitan it still runs.
That the old audio API (which by the way?) is broken in the Beta, only means that it's broken at the moment.
Some part of CoreAudio, I'd imagine, that isn't being fully incorporated or supported as part of AV Foundation. Here, go nuts. Fix Atari800MacX while you're at it.
As an aside: Logic X is in my opinion the superior product, so you should really consider buying it. I have worked with both version, so I tell that I never looked back to using Logic 9 again.
I'm sure Logic Pro X is great. I don't think paying $200 is great when what I already paid $200 for Logic Pro 9 a few years ago and that still serves my needs. I'm probably just going to spend $50 for Auria Pro on iOS and move away from using my Mac for any recording anyway if Logic Pro 9 isn't working by the final release.
Now all this petty nerd-fighting aside, Mac users can at least console ourselves that Altirra works under WINE/Crossover. Yes, it's got a horrible, clunky multi-menu Windows UI, but the underlying emulator is a wonderful piece of work that runs great, AND it supports accurate emulation of modern hardware upgrades and devices like the Ultimate 1MB, SIDE and SIDE2 carts, etc. Really fabulous work phaeron has done there.
Edited by DrVenkman, Wed Aug 17, 2016 10:45 AM.