bradberry -- The 7290 is one of the fastest BlackBerries available. (However, a 7280 with OS 3.7 is usually faster and the 7290 OS 3.8 is very slow -- but we're comparing 7280 OS 4.0 versus 7290 OS 4.0, and the 7290 is indeed faster on an apples-to-apples comparision when both are upgraded to OS4.

I don't know about 7250, it's not out yet. (Unless you meant the 7520... don't confuse the 7250 with the 7520...)

7520 is fast too, just like the 7290.

Not sure about 7100, but I heard it is somewhat slower, but that may be a symptom of its higher-resolution screen; and slower-performing theme. However, it has extra memory specs just like a 7290.

Reommended BlackBerry models for people with lots of contacts, such as 6000 contacts:
7290 and 7520