Well then here's where I'm at.
I was probably already going to see The Hobbit
within the first couple of days. And I was going to want to see it at 48fps, which probably means 3D whether I like it or not. And to increase my chances of getting both (I cynically doubt that non-3D screenings of the film would be easy to find at 48fps), I probably would have chosen IMAX at the Palms... which is the one 'actual' IMAX screen here in Vegas (there are no less than four other IMAX-registered auditoriums in town with Regal Cinemas, but I guarantee it won't be the same experience).
So with all these things in mind, I see no reason to change my plans. I would think theatrical teasers/trailers/previews are generally fair game (unlike spoilers that accidentally leak on the internet). And after all... it's the f-king Hobbit
I break for nobody.