Update: I just got my Xtraflex2 today.
I ordered the black Xtraflex2 and the silver Travelflex earlier, which I have been using for about 3 weeks or so. Looks-wise, I prefer the black to the silver because the silver seems cheap & plastic-ky to me, but the black looks very nice and seems to be made of a more durable/less brittle type of plastic.
I don't know if it's just my Xtraflex2 but the gooseneck seems more flexible and has more "give" than the Travelflex. This isn't necessarily a good thing. I feel like the Travelflex's neck is sturdier and will hold up better in the long run.
What I like about the Xtraflex2 though is that its clip seems to be grippier although my Sony Cover for the 300 was sagging from the weight of the heavier light.
I also like the fact that the Xtraflex2 can stand on its base (which I imagine might be helpful for nighttime reading when I don't want the light clipped onto my Reader or its cover).
I tested both the Travelflex and Xtraflex2 with fresh batteries and I was surprised to see that the Travelflex actually emitted a brighter light (on just one battery!) than the Xtraflex2 on one LED. With both LEDs on, the Xtraflex2 was of course brighter, but it wasn't twice as bright as the Travelflex as I would have thought it would be.
My vote then goes to the Travelflex and I'll probably be placing an order for a black one soon as my current one has gotten a bit banged up from an encounter with my dog (see avatar) last night