Just an update on this watch, I recieved permission from it's owner to post some of the photos of it here.
Above is a photo of the Electrochromic display itself separated from the module.
A photo of the complete module
And finally a photo of the watch itself, this one was taken weeks after the first two. We both thought that the display would get better if it was powered up for a week or so. Unfortunately it seems that the display can simply die of old age :( Evidence for this was in the back of my F623A manual, it had two coupons that mentioned the disply would lose contrast after 7 years and you were supposed to fill out the coupons and send your watch in with them to get a new Electrochromic display installed. (I had already contacted Seiko about this, but they told me the coupons are no longer valid lol. They don't have any more examples of the F623A movement or Electrochromic displays either.)
It's sad that you can't see what these displays really looked like when new, but it is a neat piece of horological history. :)
I'm still looking for one to purchase, even if it doesn't work, just to have an example for my collection. :)