I do alot of handheld. I bailed on the chance for RPP's for two reasons: weight/size and no 18mm. The latter being the dealbreaker for me. One day RED will have an 18mm, but between now and then I would've been one of the masses in NYC scrambling to subrent an 18mm. I see it getting ugly as rental houses will give priority to anyone renting the full set instead of those wanting just the 18.
The size factor is a big deal if the camera's on your shoulder alot.
I patiently wait to see what Illumina as up their sleeve.
Regarding the conservatism of DP's, I don't quite buy it or this site wouldn't exist. If something's better and cheaper, DP's jump on it like locusts. Look at Kinos, HMI's, RED.