I thought this article was interesting.
http://autos.yahoo.com/news/consumer...050100955.html
Consumer Reports did some testing of the latest turbos like Ford's Ecoboost and compared the mpg and acceleration to the naturally aspirated engines. It turns out you are not really getting any mpg or acceleration gains over the cheaper engine. You might be paying for a more complex engine (more stuff to possibly go wrong) that does not give you what is claimed.