Is there such a thing as a SXS compavt Flash card adapter, i.e. fit a CF card in an SXS holder? or is the physical size very diffefernt? I have PCMI adapter that allows me to use CF cards, would this work in the EX3?

Sorry if this question seems naive, I just trying to decide which camera to buy, the Z7 or EX3 and weighing up the cost factors. etc. (i am leaning heavily towards the EX3 but the media price seems very steep)

It is not possible to use a CF card (or any other media) in the camera through a simple adapter.

Apart from the restrictions in the firmware, and adapter would likely not implement the PCIe interface but rather work via the USB interface. Both interfaces are part of the ExpressCard specification, but cards can implement one or both (most implement USB).

SxS cards use the (very) fast PCIe interface which is needed to support the S&Q motion from the carmera. Also the SxS is a format that can be supported in the coming camera generations.

George/

Thank you George, I guess the media price will drop especially when third parties produce their own versions,

Prices will drop, but will always be higher than generic memory/cards. Professional media with higher quality control for a niche market is simply more expensive to produce than GA consumer media.

So all we can do is hope ;-)

George/

P.S. Sandisk branded SxS is already less expensive than the Sony branded cards.

Data rates and transfer speeds are much higher for SxS.
Right now you've got Sony and Sandisk making cards. Many moons ago Sony claimed they would make provisions for other 3rd party cards but that has not transpired.