I'm unilateral, and have been for nine months. But although my hearing is much better with my CI than with my HA (both anecdotally and tested), I do *far* *far* better with both. It's true that there are some interesting phenomena regarding the integration of stimuli from both, but I suspect a large part of the effect is due to being binaural - eliminating head shadow and having interaural timing as a noise-reduction tool. If my left ear gets significantly worse (as it's expected to, eventually), I'm definitely going to consider going bilateral.
DeafDyke is right, I think, that going from no CI to a unilateral CI is much more than going from unilateral to bilateral. But to say that it's just nice to have? Are you sure you don't work for my HMO, DD? 'Cuz I seem to remember hearing that my hearing aids were also "just nice to have", and then that bilateral aiding was "just nice to have".
