I would certainly favour the last 3 letters, as practised in the US. I also like the practice of using the type, ie. "Cessna 49Q" because it helps greatly in identifying traffic at uncontrolled fields. (all part of the broader picture in the rather narrow FISO debate raging elsewhere, in my opinion).
Englishal: A question. Quite often my call "Cessna etc." is read back by ATC as "November etc." with quite a big emphasis on the "November" part, almost as though I'm being put right. Is the Cessna part incorrect practice now in the US? Or is there some other reason why they want to emphasis the "November". Or is it my foreign accent!!?