Umfaan - an excellent small knife.
I think most people have a need/use for a knife that is smaller than 2.5 inches.
I think it is by far the best of the high-end factory or semi-production folders, although I have not ever had/handled a House of Koji Hara knife, so there may be something there.
As you know Matt, I recently switched from an Umfaan over to a handmade Kansei Mitsuno 2.25 inch monolock folder. It is a very beautiful piece of pocket jewellry and every bit as effective a cutting instrument as the Umfaan. My only compliant on all of the very small folders is that the one-hand opening aspect is always a bit akward. The Umfaan lug is very small, and I could not always reliably catch the lug. The Mitsuno folder have a very innovative sleeved thumb stud that is more reliable. The only down side of this design is that the stud reduces the effective cutting length on the blade, wheras the lug on the Umfaan does not.
A trade off then. The Umfaan is very thin and you can put it anywhere without having a knife signature. The Mitsuno is much more beautiful, but I have to carry it in a leather pouch at work (clipped at other times).