Thanks, that gave me a lot of things to consider. I had not thought of the trade off between responsiveness and harshness with 559s as contrasted with the lack of responsiveness but comfort with 622. I also had not given much thought to road conditions, gearing and style of commute (more rural with long stretches versus more stopping/starting in a more urban area) . I also liked that article on the Thorn webpage.

I'd primarily be using a bike with one of those tire sizes, 622 or 559, for a 25 mile round trip commute, mostly on the MUP in the Washington DC area. I might use for it shorter trips on the weekend and the occasional tour but now I'm so time strapped (toddler, job, old house repair, etc.) that would probably be a few years away.

Maybe it reflects the fact that I currently am using a well inflated 559, but the MUPs I use seem pretty harsh and clearly have lots of ruts from tree roots and the like. At times I hit a smooth spot on the trail and have one of those "Ahhh" moments (think of a coffe drinker on a cheesy 1980's commercial for Folgers or Maxwell House) coasting along on smooth pavement.

I don't have much experience with 622 sized tires so maybe I need to rent one and try it out for a longer ride so I have some basis for comparison.