The "even frames" method of comparison you describe is flawed. Motion blur is very important to our perception of motion, and is the reason that motion at 24fps can look great on exposed film (lots of blur) and terrible in video games (no blur). When you skip half of the frames you have thrown out motion blur information that could have been present had the lower-rate source been created at that rate in the first place.

But yes, It would be neat to experience some legitimate side-by-side comparison of frame rates / motion blurs. Such a comparison has subtleties that make it hard to do fairly and cheaply.

http://100fps.com/how_many_frames_can_humans_see.htm (edit to fix small typo)

Might this be the reason that I've heard complaints about choppiness of pans in The Hobbit at 24 fps? (When they show a 24 fps version of a 48 fps movie, do they just drop half the frames?)

Yeah, the correct way to do this would be to use two cameras set up facing a mirror, or something similar. One camera records at 24fps, one at 48fps.

If you are on Windows, you can try SmoothVideo Project:

http://www.svp-team.com/

It's just interpolated 60 fps from regular frame rate movies but it works pretty well (it needs decent GPU for high-def videos).

I use it already for quite some time. Once you get pass the initial weirdness there is kinda no way back, 24 fps movies just feel broken.

It's similar to how computer games feel bad on underpowered graphics card, you do notice choppiness of 24 fps and it is pretty distracting.

BTW I did see Hobbit in 48 fps and it just felt "normal". So I suppose most of people complaining about 48 fps Hobbit just didn't get used to high frame rates yet (I expect for many it was their first experience). For me it took me few weeks for "soap opera effect" to wear off.

I haven't seen it yet, but the flicker of the movie is very distracting to me. Especially on bright scenes, like face-closeups. Then I can see the entire screen flicker, and I get headaches like it's 1998 again with the 60hz CRT.