Renderman is great at many things, but it's not the end-all-be-all of rendering either. It lacked Global Illumination for many years, for example. Even today Vray and others will generally best it in quality and render time where GI, caustics, and other advanced lighting systems are in use. Renderman is particularly good at displacement and motion blur, in fact TG is good at both as well for similar reasons, but those things come with trade-offs as well, which make it not ideally suited for all uses.
Regarding Messiah, I'm pretty sure it uses an *old* version of Arnold which is far from the modern capabilities. Arnold does look quite interesting and capable and I believe it's supposed to be finally released to the public this year after being used with great success in a number of big Sony blockbuster films (e.g. Cloudy With A Chance of Meatballs).
- Oshyan
