Does it really matter where they come from? As long as they come to get me before I get my head cut off on Al Jazeera, I really don't care.
The CV-22s are with AFSOC--they primarily do infil/exfil of the various flavors of specops.
The H-60s are with ACC--they're the ones who are supposed to come get you. I can see why they'd want to stay with one type of helo, but I can see a greater chance of needing an H-47's high/hot capability than having to fit in an area that a 60 could get in but a 47 could not.