I have the U3 and love it. It took some getting used to, but i can type relatively well on it. Sometimes, my fingers hit a few keys at once. The major winning feature of the Sony U models are the placement of the pointing stick and the mouse buttons. I love the specs on the JVC interlink, but couldn't imagine trying to use the pointing stick in the middle of the keyboard on such a small computer. On my U3 (and also on the U101) the pointer and buttons are placed in such a manner that you can hold it like a gameboy. It's very nice, and can pull it out unseen during lectures all the time, and its very easy to carry onto planes or car rides, or pull ouyt during a moive that you decide you don't like anymore.
I had considered upgrading to a faster model like the JVC, but am going to wait until the next sony U model comes out . . .their design is just too good to move away from.
My 2 cents.