I believe the "friction" drive to be the better option for the reasons you describe.
If the entire length is driven then slipping won't be an issue. Unless someone plays funny buggers and grabs the stock to check?
You couldn't do square or rectangular sections in this method with making additional components like adapters that slip over the stock to give it a round profile to enable it to roll, which would be placed at strategic positions along the stock.
I don't believe you'll even need that many contact point on the supports. 3-4 over a full length of pipe/tube (depending on wall thickness/rigidity) would be plenty.