Chopper,
There are a lot of reasons why you'd like a V-22 over a Merlin Mk4. Speed, range, height and payload all spring immediately to mind (and have a look at the improved range/payload specs for the CMV-22B) .....The Merlin has two main advantages over the V-22. It is expensive, but not quite as expensive as the V-22, and it's nailed together in Yeovil....