After doing some reading last night about tweaking W3TC, I decided to change my Object Cache and Database Caches to use Xcache (rather than disk). Making this change has dramatically sped up load times on my sites, but completely killed scheduled posts. This morning, both posts I had scheduled on the two sites I made this change to didn't post as they would have previously and showed as "Missed Schedule" in WordPress.
Obviously I'd like to continue using Xcache if at all possible for the Object & Database caches - the improvement speed-wise in both sites is pretty dramatic - but I need the scheduled posts function to, umm, actually work. Help?