Wahey, its the TT vs V8 debate again B) .
Its personal preference I guess.
I suspect if MPG is a concern then I dont think anyone buys a Soarer for its fuel efficiency, but having said that they are a nice practical hi performance luxury coupe. If you expect 22mpg then you'll be around the right figure overall.
If its the looks and style and reasonable performance / mpg then there are more and more 10 year old 3.0litre variants. They were made from 1994 onwards and are appearing in the car ads now.
V8's have all the luxury kit. Some versions of the TT are "relatively" basic. Not sure about the 3.0 litre. The Americans seemed to like them well enough.
Be content that whatever the model you will have something a little different from the norm with an excellent owner support network (here and TIF). Toyota / Lexus reliability and build quality too.