I just wish that 3D rentals were an option via my Netflix disc subscription.. I saw this in a real IMAX and loved it as most did due to the immersion aspects and I just don't know that the experience would be enough to make me want to watch it more than once on my home 60" passive (so some detail is lost) 3d screen. Certainly not interested in 2D as that would unquestionably remove the immersion and I'm not watching it for the distracting bit of forced 'hollywood' story that is there. I'll have to check redbox and local safeway to see if they rent the 3d version.
As to the "buy Blu-ray vs. stream' questions, it is very easy decision for me. Blu-ray is the highest quality source available and it is the only on you actually own a copy of. "Buying" movies from iTunes/Xbox/Vudu/etc is just getting extremely restricted viewing rights that are for folks who didn't learn anything from the DRM'd music days. Also, while Disney is messing things up a bit, most new Blu-ray's come with the online licenses (Ultraviolet or the Disney/Apple whatever) now so you not only get the highest resolution physical media, for no additional money you also get access to the online version that (again with the exception of Disney-Apple) isn't tied to any one provider. There is also the ability to buy at a price advantage due to steep sales, bargain bin's, used media, etc that you rarely see, or is impossible, with 'buying' online.
Blu-ray = Highest resolution local copy, with all the extras + online viewing rights accessible via a number of services (unless it is a Disney title - then just their site)
Online = Online version accessible only via the service you paid (unless you bought from a UV provider). Usually no extras, audio and video quality is wildcard. Service goes away or studio or provider decides to remove viewing rights, you have nothing.