I think OP is more interested in feedback for the older Athena than 11 speed. Athena didn't come out until , I think, 1988. I have one bike with complete '89 Athena and a couple of others with similar vintage Athena bits. It works well, no problems. Aesthetically not quite as pleasing as the higher level C Record stuff, but still looks nice IMO.
The Athena rear derailleur from this era used an insert on the mounting bolt that tended to break, or more frequently, get lost when RD removed, so make sure it is present if you buy the derailleur as they are hard to come by.
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N = '96 Colnago C40, '04 Wilier Alpe D'Huez, '10 Colnago EPS, '85 Merckx Pro, '89 Merckx Century, '86 Tommasini Professional, '04 Teschner Aero FX Pro, '05 Alan Carbon Cross, '86 De Rosa Professional, '95 Gios Compact Pro, '95 Carrera Zeus, ‘81 Masi Gran Criterium, ‘81 Merckx Pro, ‘89 Cinelli Supercorsa, ‘83 Bianchi Specialissima, ‘VO Randonneur, Ritchey Breakaway Steel, Rivendell Rambouillet, Heron Randonneur, ‘92 Ciöcc Columbus EL