Faster than the original Evo?
Easily MUCH.
If you keep up with CPU architecture, you'd know that the next generation offer more bang per Mhz and does it with less power.
Check out this comparison of the G2 versus the NExus 1:
T-Mobile G2 benchmark result leave Nexus One behind
The chip in the Shift is the same as the G2's I think. And the Nexus1 shares the same first generation Snapdragon as the EVO.
In general, Mhz can only be compared on the same generation, even on desktops.
For example, a Pentium 4 3.2Ghz is actually far slower than a Core2 clocked in at 1.8Ghz, and the newer architecture is far more energy efficient to boot.
This is, btw, one of the reasons the EVO is getting long in the tooth... it can even be trumped by the "lowly" LG Optimus in some 3D games. OpenGL test rated the 600Mhz Optimus S with 15fps MORE than the EVO, and its a budget (free) phone whereas EVO is supposed to be a flagship product!
800mhz will be faster and the battery will last longer on the shift (smaller screen helps too). This sounds AWESOME.
Now, back on topic- will this thing get a FFC camera or not? Because if not, I'm not sure its worth the upgrade versus something like the Optimus. (no 4G fee works for me!)