Are Hayes MX1 and MX2 disk brakes interchangeable?

My bike currently has 6" MX1 brakes on it, and I need to replace my front brake. I found a good deal on the internet for a MX2 caliper and rotor set, so will it fit right in with no tweaking? I plan on using the 74 to 51mm converter that's currently on my MX1 that I'm tossing out. Thanks!