There are different 70mm prints out for 2001 by the way and the one I saw a few years ago looked more like 35mm so you never know what you get before you attend a screening of 2001.
I remember they struck a couple new ones for the late 2001/early 2002 re-release - I believe they actually shipped a 70mm projector with the print to certain locations. I remember reading at the time that they had made two different prints, and I remember seeing both in different cities. There was a 35mm print that had been used in the NYC area by several different theaters, I started to recognize familiar scratches from different viewings over the years Still, even with a little print damage, it was always incredible. 70mm was my preference but 35mm wasn't bad either.
I've seen the "2001" DCP projected on, I think, three or four different occasions, and to me, there's virtually no difference in watching that DCP vs. watching the Blu-ray at home. The revival screens aren't that much bigger than a large TV anyway, so the whole experience isn't optimal. It's usually misframed too - I imagine it's encoded with the 2.20:1 image inside a 16x9 frame, and the last couple times I've seen it, they had the screen opened for 1.85:1, and then black bars projected as part of the image. They also let it run without a break during the intermission - the title card comes up, the lights stay down, and the entr'acte just starts right up. Ugh. Either skip the intermission title card and the break music, or actually take an intermission. No one seems to care anymore. I'll admit, I'm the guy who still has a record player, so I might just be a snob.. but when I go to a theater to see a showing of a classic film, I don't want to see the Blu-ray I have at home, I want to see an old fashioned film print, something that I could never show in my home. If it's just going to be the exact same experience, I might as well save the cash and stay put.
I'd love to make it out to Seattle one day for their 70mm festival. It's just sad that in a big city like New York, you can't even see a film shown on film anymore.