HDfury4 (or 3Dfury) can output 1080p as 1080p24/48/50/60/72 (user choice)
it can output 720p60 at 720p120
It can also output 3D at either 720p50/60/72/96/100/120/144 or 1080p/50/60/72
24fps is too low for 3D (12frame per eyes) its unwatchable
Just read the customer feedback on the hdfury website
It's easy to understand once you have the stuff in hand.
You just select the High Frame rate on if you have 100/120 or CRT, or off if you have 50/60hz display.
Once done, you just click the frame rate button (with the movie icon) and it will cycles between each output mode available.
If your display is 60hz, then you need 3D @ 1080p60 or 720p60.
If your display is 100/120, then you need 3D with high frame rate.
Since CRT projector and other CRt devices can sync with mostly anything.
You can setup 1080p to be output up to 1080p72
or up to 720p144
Now, this is getting even more interresting if you build up a dual projector setup with silver screen and polarizers, using passive glasses, you can go up to 1080p144 or 720p288