So after a lot of research from here and other sources, I decided to pull the trigger. With the service history being minimal, I felt as if this one was better than any of the other 50's I was looking at/test driving. This was also the lowest mileage, better price than most, and best optioned of the cars I was viewing.
Couple of thoughts: Night and Day difference. My 45 feels more like raw aggressive power, but the 550 has so many creature comforts and refinements.
One thing that sorta worries me is the lack of service history. Only minor maintenance thus far (battery, oil, brakes, fluids etc) and two back to back HPP's (high pressure pumps?) And the build date of February '11
Production date: 24.02.2011