I found a satisfactory workaround. Running mplayer with the gl renderer, framedrop, autosync 30 and the opengl vsync set to the tv with __GL_SYNC_DISPLAY_DEVICE the 24 fps videos work silky and smooth. Framedrop is essential for keeping the audio in sync. Without it, the sync drifts terribly whenever the playback fails to keep up the pace. When that happens, now there are subtle hitches at worst whereas xv would go berserk twitching frames back and forth. Seeking in the video is a little choppy but the playback settles down after a while, apparently after the next keyframe.
I took quite a while to figure this out. Too bad nvidia hasn't bothered to fix their xv implementation or respond to this thread. Well, using the gl output has the added benefit of better scaling when lscale=1 and cscale=1 are passed to it. Using fragment program colorspace conversion with yuv=2 reduces cpu usage to amounts comparable to xv. I guess I won't bother with xv anymore. By the way, can the gl output be used with vdpau?
Despite sounding negative, I'm going to happily enjoy my judder free movies now for the first time.