[albanycobra]

Stephen , honestly it comes down to the ability of the tuner to get a result. The best ECU in the world will drive like a pig with a bad tune and cost you a fortune if the Tuner has no idea on that brand.
If your local dyno Guy is a Wolf expert then go Wolf. I looked at the V550 its a good ecu but will need additional modules wired in to fire the AU coils, easy job.
I am in a similar situation to you ,but I do all my own tuning and have access to a dyno so life is a little easier, I think the Motec M800 is the pick of the bunch but the M84 will do me.

If you use a piggy back chip you may have to use the airflow meter were the others you can remove it. Contact TI Performance as thats where i get my chips from in Vic and Jason does a good job and they can tune your car if you live that way.