I think your BMW master tech is correct. That would be the worse case sernario for oil consumption.
Since you are past the 1,200 mile service... I would take your M3 out for a nice long drive. Make sure everything is fully warmed up. Then take the revs up in 3rd or 4th gears. Do a few light loads - in 3rd gear up to read line. Or better yet... first say to 5K, 6K, 7K, 8K... drive in 3rd until those rpms... then let the engine coast down in gear. Doing this three or four times and your engine will be fully broken in.
Reving the engine @high rpms and then letting it coast down in gear is good for the long term life of the motor (when the engine oil is fully warmed up!). Doing this when the engine is new - will break it in. You always want to vary the rpms and load of the motor. This will seat the rings and valves inside the motor.
I would not get too upset with some oil consumption for the first 10K miles or so. After that... your engine shouldn't use much oil. But then again... I wouldn't be going with BMW long OCI(oil change intervals) anayway!!!