shooting on arriraw is not as easy as shooting uncompressed with recorders like the stwo dfr2k and ob1.
if you have the luxury of time shoot arriraw, manage the files, and then debayer it, it would be great to shoot on arriraw.
we have been shooting uncompressed with our stwo dfr2k and ob1 recorder for almost two years now, with our d21 and now the alexa.
the uncompressed raw dpx from the dfr2k shot on log c is really very good, plus the workflow is not that tedious.
we have shot a feature last year which the director one best director, "the execution of p" shot with the d21 recorded on stwo dfr2k, when it was blowed up on film, the output was really amazing.
just to sum it up, if you have time to manage files and debayer the arriraw materials, go for it. but shooting uncompressed dpx hd 1080p will do the job for you.
i promise you, when you view the arriraw images and uncompressed dpx side side... by eye you wont see any difference... it's just the psychology that i am shooting arriraw that gives you the wow factor.
hope this helps.
mark