I am by far the last person to ask in regards to if direct injection is the best, but I thought I might pass along some info. The turbo Mazda's are having a real problem when modified for higher boost levels with direct injection. It seems that they are finding the intake air stream has a huge effect on if the fuel makes it to the spark gap. When boosting at higher cfm and pressure levels they claim that things change quite a bit.
Typically our injectors are in the intake track and the fuel charge seems to get atomized better and becomes part of the air charge eliminating that issue.
I might be wrong, certainly time will tell if it is superior on a GM engine. From engine to engine I am sure these things can change.