I have the diamondback and I really like it. This after using the Logitech MX1000. The diamondback is lightweight and easy to hold. Getting used to the shape took sometime, but now its a breeze to use. Also it has on the fly sensitivity adjustment. Unlike the G5, with 3 preset sensitivity settings, the Razor on the fly can adjust the sensitivity levels between 1-10. Only downside is that if you want to use the on the fly sensitivity, the only button that you can set it to is the side thumb button. Which may cause an inconvenience for those who use it for other things or a "back" button while browsing the net.
All in all, for that price, you might as well get one and try it out.