Sinus Lift or No Lift?

Dr. Meniga asks:
Recently, we had a discussion in my dental implant study club about the placement of a 10 mm dental implant fixture in 9 mm wide bone under maxillary sinus.

Some of my colleagues think that a crestal sinus lift should be performed first. Some of my other colleagues (including myself) prefer the stabilisation of a dental implant in the sinus floor in spite of possible laceration of Schneiderian membrane. In other words, no sinus lift. What are your experiences? What are your protocols?