In reply to Bob:
My experience of On One isn't great. I used to work in a bike shop and we would often see badly welded and out of line frames from them. This was 2005/2006 so probably well out of date as I'm sure the production has improved since then.
The Genesis High Latitude that I mentioned in the other threae isn't a bad full build and they're super playful to ride....
Also, Ragley Blue Pig, Dialled PA, Cotic Soul, I haven't checked their websites but I'd imagine they will all do alternative wheel sizes in those models.....