I have been pondering... my Twenty runs out pretty damn fast with it's 1.35 Comets but is set up for touring so suffers from being a little weightier and building up a 451 road model would be fun.... the larger wheel would help with the road gearing and they do make for a pretty nice ride.
But then again... I could just go and build up a frame to accept 451 wheels and this would be easier than having to do all the modifications to a stock Twenty as many hours have gone into making my little Phillip's what it is and there is still more work planned.
And unlike many, I don't care that my bike folds as it rarely has to do that.... I just love riding this bike.