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danb-
Correct. 10 speed eTube shifters (i.e. 6770 and 10 speed non-series) shifters will work perfectly well with 11 speed derailleurs even if they are all updated to the most recent firmware. That's the set-up my Brommers Bike #3 has, and it was working just fine and dandy yesterday. The only thing that won't work is a 10 speed FD and 11 speed RD with more recent firmware.
Brommers
Apparently the old 10 speed shifters only work with 11 speed stuff if they weren't updated to the latest firmware version, so you do have to be careful, but yeah for the most part they'll work