I do have one and i regret it...sometimes...
Heavier and longer than a 416, the 5-pin cable is a bit unhandy when you want to change your microphone in a 'run-and-gun' situation, you lose 2 channels because both the M and the S microphones need phantom and the S-microphone is quiet noisy!!
...but...
It's just like a 416 (a great allrounder), stereo is always a gigantic 'pro' and you've him always with you (it was my first shotgun), great for loud ambiences of crowds and scènes with cars involved!
I'd recommend using an ambient emesser with a regular 416 or other microphone for a cheap M/S-solution...
Jeroen