I can confirm, that the choppy playback while using audio sync isn’t a problem in OSMC.
But to be honest, I only used this audio delay function exactly once - just to test, if it is a problem in OSMC, too, and this is really the ONLY problem I’ve seen with CoreELEC in the current stable/nightly builds.
You should keep in mind, that Kodi itself is still in beta stage, and there are still a lot of bugs contained.
The main question should be: Why is audio sync this important to you?
Are most of your video files out of sync (bad rip)?
If it is because of a delayed video on your TV (video processing of the TV itself), there should be an option in your AVR to compensate that (auto delay/auto lipsync/…however it is called in your AVR).