I had an S&W model 66 with a 2.5" barrel, and when I carried it I liked it best in a no-name OWB holster with an FBI cant that I picked up at a gun show. I carried it at about the 4-4:30 position with a shirt or a jacket over it, and it worked well. These days I carry a semi-auto in an IWB kydex/leather hybrid. I don't think 6-shot revolvers lend themselves as much to IWB due to the width of the cylinder, but it's an option. I think you get the best concealability with IWB, and for IWB you get the best all-day comfort from a kydex/leather hybrid. In terms of overall best comfort I'd say the OWB is better, particularly with a wheel gun.