Thanks Paulo; didnt notice the CR.
I think the relative aft placement of First 40 mast is to allow for a larger blade jib for pointing. The Centurion being a Cruiser-Racer probably has the mast further forwards to allow for a bigger main and an overlapping jib - #2 say - with the jib not meant to be changed often by Cruisers.
Anyway, the Centurion 40s was first built in 1998 (I think) and I find it interesting that 10 years later a very similar hull is being used on the First 40. These companies must be using the same finite element analysis software.