My first question to you - did you test drive it ? If not, don't sign over the dotted line just yet. Take it for a loong spin, on your favorite "test track", and drive the wheels off of it. If it wows you more than the M3, then there really isn't any decision to make.
If it doesn't excite you as much as the sauerkraut sedan, then go home happy.
2004 Z4 3.0
2014 X1 28i ED
2015 F80 ED in June