I think I'd use a button like that, but I depend SO much on the double click that it's highly annoying when using a normal mouse.

I could get one of the new Logitechs, and I want to, but I have a single complaint that keeps me from buying any of them: I love having the tumb button on the side-bottom, not the side-top. The thumb button is always there and I don't need to move my thumb at all to use it. I know it seems tiny, but given the number of times I use it at one sitting, I know it would make for a frustrating experience.