The following is about 3:2 pulldown judder, not film judder. Film judder is the choppiness of motion created by film's inherently slow frame rate (24fps). I make the case that it is technically accurate to say that any 3D display that is limited to 120hz will introduce 3:2 pulldown judder for 3D 24p source playback.
The math for 3:2 (or 2:3, same thing) pulldown is pretty clear for 3D, even if how the manufacturers implement it is not. If any given frame is displayed 3 times for one eye and 2 times for the other, judder is introduced. Now, maybe the sequential nature of the display (even if they do 3L:2R, 3R:2L, etc.) makes for a less obvious judder, but it's still judder. Only if each frame is presented an equal number of times to each eye can the display be completely judder free.
Material shot on HD video can be judder free at 60hz - either 60x 1920x540 interlaced fields per second (1080i) or 60x 1280x720 progressive frames per second (720p). No 3:2 pulldown is necessary when HD video is shot at either of those frame rates. Of course, HD video can be shot at a film frame rate, too - 1920x1080p 24 or 1280x720p 24. That's when 3:2 pulldown becomes necessary with 2D displays that have a fixed 60hz playback rate.
A display that is capable of doing 120hz is perfect for 2D, because 120 is equally divisible by 30, 60 and 24. Each frame (or field) is presented to the viewer the same number of times. The problem is that a 120hz frame rate cannot display each frame of 3D (48 left/right eye views) an equal number of times (as it must for technically judder-free frame sequential 3D). 120 divided by 48 is 2.5. That means that a 3D display with a refresh rate of only 120hz will introduce 3:2 pulldown, and judder. Will it look smoother than 3:2 pulldown of 2D material on a 60hz display? I don't know. Maybe, but eliminating judder altogether at that frame rate for 3D is not possible.
The next frame rate up from 120hz that will do judder-free 24fps 3D film (48 total frames per second) is 144hz - 3x48=144fps. Each eye sees each frame of the 3D pair 3 times each - no judder. A good 3D display could sync to 3D video at 120hz and 3D film at 144hz. (When I shoot HD video (in 2D, obviously), I shoot at 1920x1080 30p, since all of my work will be shown on video, never in a commercial theater. It makes things like slo-mo that much easier in post.)
The HDI laser rear projection system takes that whole idea to another level with color sequential 3D. It uses passive 3D technology, with 2 LCOS chips, one for each eye, to display its images like DLP, but much, much faster. It has a frame rate of 1080fps - for each eye! (It's passive 3D, so both eye views can be on the screen at the same time.) Like DLP, each frame is divided into its RGB primaries - the red frame is flashed, followed by the green, then the blue, which the eye blends into a full color frame. Thus, the system displays 360 full frames in one second (1080 divided by 3, for each eye). 360 is equally divisible by 24, 30 and 60, so judder can be eliminated altogether. I just wish these guys had the funding and manufacturing capabilities behind them that the big names in TV have. I find this technology the most interesting of all.