I post mix nearly every recording I make since I usually run more than 2 mics.

The R4 makes it super-easy, no drift, and only a minor delay is needed to remedy any timing differences.
BTW, I recently spot-miced a trio with the R4 for a post-mixdown. It was one of the few times I didn't run any sort of a stereo pair at all -- just one mic per instrument. Had some phasing, but it was a fun little production project. I also synced some of it with video for one track. It's the top post in my blog right now.