Motion sickness usually come when the VR is lagging being your head movements. Headaches and eyestrain are often a result of the active shutters in the 3d glasses. The Sony VR is said to be tracking very well and there are no active shutters.

Exactly. The sickness is largely caused by too much latency, as well as blurring/smearing of your "vision".

This is why low latency and low persistence are so important. Latency in this case refers to the time from when you turn your head to the time that your perspective changes. Oculus often refer to this as "motion to photons" and they want to get this under 20ms for the consumer Rift.

Low persistence is the other technology implemented in the new DK2 version of the Rift and it has to do with how long the pixels stay "lit". The new OLED panel in the Rift allows them to turn on and off pixel elements very quickly to reduce the blurring and smearing that you get on most displays. It helps tremendously with image clarity while in motion.

Improving both of these factors goes a very long way towards minimizing motion sickness in those that are prone to it.

I heard 98.9% of Xbox fanboys get motion sickness and headaches ...Research shows though once MS lets Sony do the heavy lifting on VR and announces their own VR helmet...Motion sickness and headaches will fall to 9.4% for Xbox fanboys....