I am a very tight knitter and when working stockinette in the round I have trouble sliding the stitches on the left needle. I have found that just using a tip one size smaller on the left needle makes it easier to keep things moving, and it doesn't affect my gauge since the right hand needle forms the stitches.
On the other hand, when working stockinette back and forth, my gauge with purling is looser, so if I am having a big discrepancy, I will put different sized tips on my needles in order to use a larger one for the knit side and a smaller one for the purl side. I guess these only work with interchangeables - love my Options!
I am trying to tighten up my purl stitches to match, but with some yarns the difference is more obvious. Also, when I get tired or stop actively thinking about it, the purl stitches get looser again.
PS - Jack did you go to NCSU? I went to vet school there (Carolina for undergrad)!