Snak -- fine watches
Graham, Omega did not begin using ETA movements until the mid-1980s, 1985 in particular.
However, Omega became unfocused by the mid-1970s, with technologies and designs all over the place. They were selling mechanicals, automatics, quartz, megaquartz, tuning forks at several frequencies. You did not know what to expect from Omega from 1975 to 1985.
I agree with your assessment of the period as the "wilderness years".
Nonetheless, some watches from that period are quite attractive and share a place in my collection.
Sam
4,430 Omega listings are live on the eBay market and 357 collector listings on the WatchProSite marketplace.