Ended up choosing option (b) and collapsed when I got home last night. Watched a little bit of The Matrix in HD, just wanting to see how big a difference there is, and... well... yeah, there's a big fucking difference. Actually, there's SUCH a big difference that it took me out of the movie. Case in point: the movie's introduction, where Trinity is being chased over rooftops by an Agent. Now, I've seen the first movie many many times, and I've seen the making-of docs, but this was the first time where I could finally tell that this was all a set - the cityscape background is now obviously a 2D background, and I could even see the black curtains on the ceiling of the stage.
Tangent: a lot has been said that it was the porn industry that ultimately had the most to do with settling the VHS/Beta format war in the 80s, and that they may have a hand in ultimately sealing the deal between BluRay and HD. All I can say is: I'm not sure that porn needs to be seen in high definition. In fact, I'm pretty sure that it shouldn't.