[Yashinoff]

Do you have another reference for the 1954 Wirgin Edixa Reflex? This site states a different year -> Edixa Reflex (1957). Perhaps a different model?

Of course arguably the single biggest advancement that opened the SLR floodgate was Asahi's instant - and automatic, mirror return.

Yes the Edixa line was well established, and actually quite popular by 1957.
A list of the variations of the Edixa Reflex is found here: http://anusf.anu.edu.au/~aab900/phot...ras/edixas.htm
Another page about the history of the Edixa Reflex is this one: http://photobutmore.de/vintagephoto/edixa/modelle/

My personal experience playing with old SLRs is that the automatic diaphragm was a more important advancement than the instant return mirror. Having to stop down the lens manually can easily cost you a great candid photo opportunity. Not that Edixa invented the auto diaphragm, it was introduced for the M42 mount the same year by Pentacon, and had already been implemented a few years earlier on the Praktina. As well as there were the Exakta style pressure activated diaphgrams used by a few companies.