I have a slightly earlier pair (serial number begins with #65). Although, regretfully, I seldom feel they are the best choice for my birding, there is a lot I like about them - the generous field of view is always a pleasure to look through, edge performance is actually fairly decent at closer range (though, somewhat oddly, seems to fall off when looking at targets further off)they are surprisingly bright for a single-coated binocular. They seem very well built, better than the East German Zeiss Jenoptems I formerly owned and not far off the superbly built Zeiss West porros. You probably won't think they handle as beautifully as your Zephyrs, but if you're observing flocking behaviour, from starlings and so on, they are brilliant for that.
It's a pity this type of binocular was not, it seems, popular enough to get the upgrades that the 8.5x44 Audubons had. A fully multi-coated #766, ideally with the eyepiece design tweaked for a little more eye relief (I have to place my eye closer to the glass with this than any other binocular I have) and a little better edge performance would be wonderful even today.