After a lot of speculation we have just got confirmation that DOA4 is region free from one of our customers in germany that the game does indeed work on a PAL Xbox 360 Console.
Here are excepts from the emails :
Got the game today and it works like a charm. Thank you for the fast shipping.
I then emailed to confirm 100% that it worked on a PAL system and got the following reply :
Yes, it works without any problems on my German PAL XBOX 360 System, And has multilanguage screen text.
So this is great news for all you importers so order away!