What a great thread! I also used to race the 210 before it opened, what a blast from the past that was. I was too poor to afford fast enough cars in those days, so I went to motorcycles and for many years it was bikes for fun and fast, and cars for transportation.
Many years later a friend at work showed up with a used Boxster. I couldn't believe how cheap she got it, or how much fun it was to drive- she actually asked me to show her what it would do!!! Anyway, that led me to spending 2 weeks looking for the car that was the most fun to drive that I could afford.
I am now on my 3rd BMW, and can honestly say I wish I'd kept them all- a Z3 coupe (that I sold at a nice profit), an 03 ZHP, sold just before 100K, and my current 06 330i that has 140K on it and still looks, feels, and drives like new. For me the choice between MB and BMW is luxury versus performance. At least the last time I looked, MB runs heavier and much more expensive for comparable performance.
I also have had some very fast bikes, and I can say that a sporty model BMW (haven't tried the 5 series) is almost as much fun in traffic as a bike, but much more comfortable- and I can drink my coffee! I have had no unusual problems with any of the Beemers, and they only need to go in for oil every 15K or so. I did have to replace the water pump at about 120K.
As far as cost, I've usually paid about the price of a new Accord. Buying certified used gets me a 100K extended warranty and I pay somewhere around $1200 for an extended service plan. This makes my actual cost to own considerably less than the Honda. I actually thought about going back to Honda once, but a test drive quickly showed me that I was now spoiled.
I had always thought of "Beemers" as yuppy cars and for posers, but after driving everything that might be a match, they really are "the ultimate driving machine". The Porches are a notch up, but at considerably more cost, higher maintenance and much less practicality. The Corvette, for me, was just overkill for the street- like using a sledgehammer to drive a nail- awesome car, but how often can you really use that much power, and I've got 4 doors and a huge trunk in a car that doesn't seem to attract a lot of attention from the police (so I get to actually drive the piss out of it and get away with it- ever notice how may Porches and Corvettes are doing the speed limit?), so I couldn't be happier. The balance, feel, and real-world performance are just amazing for a car that doesn't ask you to make any sacrifices.
Final argument- go test drive a 335i and report back.