In good old tradition, I broke my XDA Orbit touchscreen in the summer of 2008, and after a bit of cursing I bought the XDA Diamond, originally known as HTC Diamond. Compared to the Orbit, it is sleeker but heavier, and has double CPU, double RAM, and most importantly double screen resolution (480x640 instead of 200x320).
On the downside, the battery life has worsened, and there is only 1 programmable button (in general, the "Menu" and "Ok" button are missed). The TouchFlo 3D interface is nice to handle but seems to be a performance hog, making the Diamond feel slower than the Orbit, even though its CPU is twice as fast.
|O2 XDA Diamond||Evaluation|
So far, I preferred the XDA Orbit, although the Diamond is objectively better (except for number of buttons). That said, it is still a very good phone: All connectivity, navigation, decent camera, and with TF3D Config even a good GUI.