This one's not listed in the "official" Firmware Changelog thread by Motz.
It has been a few years now, of course, but this f/w is higher than the stable f/w listed and I seem to recall this one released right before ceton pulled the plug. My echo was on android f/w and I never got this one but an echo I aquired recently on ebay has it.
It seems to work OK with some macroblocking more visible than on any other echo in my collection. I don't know if it is this f/w or the fact that this echo is also the only one connected through a 5gHz ac wireless bridge which shows full strength signal from the router a few feet away on the other side of the exterior stucco wall.
Any information on the changelog of this f/w would be nice. If it was an improvement, I'll keep it. Otherwise, I will roll back. I am not sure but it may not pull this f/w again if I go on the stable channel.
That said, my previous android echo has been flashed back to 2013.304.1257 but still shows an update available for the android f/w as the f/w is keyed to the MAC Address and maybe that's the case with this unit too.
Any info would be great and TIA!