I worked on "Knowing" and I've worked a lot with RED on various projects. For every pro, there is a con (and vice versa). Really what it changes in terms of cost and workflow is the shift of expenses from one aspect of the production to another -- more money to put somewhere else.
RED is revolutionary for the ownership price/quality (see competitor's prices). Imagine an upstart company with no track record producing a full-frame M8 for 1/4 of the price... although different in many aspects, that would parallel what RED have done.
Considering the near hegemony that Panavision have in many markets; RED is gaining (gained?) traction as an "own-it-yourself" alternative (Panavision do not sell their equipment). But you would be surprised at how many studios and advertising agencies are (inexplicably) very wary of digital. This is not because of aesthetics. The correlation between camera price and quality has not been broken like this for many years; breaking formulas like that freaks out accountants and bean counters!
As far as Knowing goes, Alex Proyas has an exceptionally keen eye, and despite his cheerleading for the RED, I don't think for a moment he isn't aware of its flaws. However, it does represent the current "best case" scenario for a director like him (and, I suspect, many others).
As for grainless? Well, if you don't count the compression artefacts...