It's not taboo to mention Alexa here. I was also struck by
Drive's look. I went in not knowing it was shot digitally and was shocked afterwards- not just that it was Alexa, but that it was digital at all. The scene in his apartment where just the single work light was on was amazing. Wonderful highlight preservation, etc. You have to remember though that Steven Soderbergh shot
Contagion as with
Girlfriend Experience and
CHE using available light. On this film he shot with two wide primes (18mm and 30mm I think). He also is a big fan of crushing blacks and high contrast environments like casinos for some scenes... intentionally degrading the footage to an extent. In the rest of the film, he went for the more flat feel. So to pit
Drive to
Contagion as a comparison between Arri and Red is just not realistic at all. And, remember,
Drive... as much as I like it, will always be stuck at 1080p.
A great example of the ability of all these cameras is
Transformers: Dark of the Moon. That project used film, Alexa, Red, SI-2K, and F35. Who can tell which is which?
http://www.imdb.com/title/tt1399103/technical