I too had an Elise before selling and getting an M Coupe. These guys are drinking cool aid if they say the Elise is "comfortable" by any stretch.
The ride wasn't overly harsh but the wind noise, squeaks as the plastic dash expanded and contracted in heat and cool weather, you never felt you were in a "real car". Also wasn't good for any sort of business call should you get one while in the car.
Of course the driving experience is as pure as they come. Even better than my NSX's. However, I appreciate more about a car than its raw driving dynamics. It's build quality including structural integrity, durability, refinement when in 100 degrees all also contribute some.
So I wanted a car that was rare, beautiful - especially lowered on some nice wheels. Refined enough for business calls, good for my wife to get in and out of on a night out, great sound, feedback & handling, etc. The M Coupe was the perfect compromise of usability and exotic-ness.
Regarding people not noticing the M Coupe this may be true with stock wheels. But a nice set of wheels really transforms the Z4MC into an eyeball magnet. People constantly stare, ask questions etc.
In fact, today we went to Six Flaggs. Well I had planned to park in the general parking where rest of my caravan would be. But the 3 guys at the parking booth wouldn't shut up oggling the car, asking how much, saying they have to have one some day and INSISTING we park in the self-park valet. They said a car that nice should not be in general parking. This sort of oggling happens all the time.
Here are a few pictures of both.
http://www.cardomain.com/ride/291976