Yes, I think adding graphite filled epoxy to the track is important. I like to cut the track a little oversized and go back with the graphite filled epoxy in several thin coats. Sandpaper around a drill bit works well between coats. After a few coats and sanding in between you end up with a very smooth, much lower friction track.
I'll have to pick your brain a little about whether (and how) to do that on my tube. I just finished the dowel, and it's within 0.005" of round just about anywhere you want to measure. That bullnose bit really did the trick.