I've noticed a very subtle problem with the beatmark rendering. The marks seem to change position ever so slightly from the right side of the waveform view to the left side. Meaning, I've seen songs where the beat marker looks like it's early on the right (there is space between the mark and the waveform of the bass), but if I scrub the song to the left, by the time that particular beat gets to the left side of the waveform that little space is gone. Scrubbing back and forth, the problem is consistent -- the actual beatmarker isn't drifting, it just renders in a slightly different place depending on what side of the waveform it's on.
There might be some sort of subtle sub-pixel rendering error going on.
I'm attaching two pngs which show the same beat on one side versus the other.
the other screenshot