I did a lot of Stereo3D shorts already.
The average eye distance for europeans is 6.5cm. If you create your stereopair with that distance you should be save.
The problem is though, people with smaller eye distance, get nausia, those with wider eye distance perceive less stereo effect.
And there are certain people, that are not able to perceive the stereo 3D at all. It´s just the way it is.
For realtime Stereo3D, the calculations double, meaning your FPS will cut in half, because you have to calculate each frame twice, for each eye once.
There are only 2 real options, shutter or polarized.
Shutter looses ~70% of its overall brightness, although only one eye is covered for each frame, it doesn´t work very good with artifical light anywhere and the goggles are expensive.
Polarized is mostly contrast true, needs just cheapass goggles, like the ones in the cinemas, but you need a special display. And the cheap displays end with cutting your vertical resolution in half, as all even lines are polarized vertical, all odd lines are polarized horizontal.
All in all, I think Stereo3D as we got it now is a fail that will not prevail.
It has it´s moments for cinema and the wow effect, certain scientific applications but beyond that it is crap - and for serious scientific stuff mostly HMD´s are used anyways (head moutnted displays, two small screen in the goggles, price ~2000USD for 1024*768)
It will get intresting once we can project images directly in the eye, and base the DOF on where the eye is looking.