I would, and have, run at that oil level and then add a full quart when the engine tells me too, rather than "effing about" adding oil and waiting for a read. Currently, that level means I have to add oil in about 500 miles.
I trust the BMW engineers too tell me when is too much, and when is too little to protect the engine. Not sure what happens in the middle between the marks though, but I think the rate of loss is consistent, and the oil meter drop reflects the shape of the oil sump.
I always carry 2 quarts in the trunk...although you would only ever need one at a time, 2 just seems better.
I have 78K on my M3 and about 30 track days and I am adding one quart every 3K. It was only about 45-50K that I needed to start adding oil. Apparently, 1 quart every 800 miles is still within BMW spec!