OK, here is the info Larry Villella of ADK sent to me:
The Type III was a pure U-67 sonic imitation.
Everyone in Nashville Loved it. No one in LA or NY liked it at all!
So we came out with a simultaneous version - the IV. Much more "Austrian" sounding. All the Guys in LA went nuts for it.
Great Rock-Oriented Mic. But: the guys in Nashville hated it!
So the Version V was the first "blended" curve that we ever did,
and for the past two years has been a runaway best seller.
LA and NY and Nashville all seem to be happy with this mic.
So--Gidge--it sounds like the version V might be the one to go for--although I like this version III--must be the Nashville in me!