As far as I understand, the biggest advantages to bilateral CIs are directional hearing and more precise detail in sound.
I got my second CI when I was 12 and social situations and school became a lot easier for me. It will be ten years next year, of having two CIs.
Often, out of ease, I will only wear one CI around the house, but find that I actually battle to hear more than one-on-one conversations without two. Your classic plasticity argument.
However, when I'm in situations where both my CIs could get damaged, like walking in the ocean, wearing one is a good sort of insurance.
My favourite con would be the cost of an extra CI's worth of batteries and parts to maintain - I live in South Africa, and here, batteries aren't covered by insurance, or government. Parts, however, are covered by insurance. I'd say, just be aware of those potential costs - though Cochlear and MedEl both have rechargeable batteries - I use rechargeables myself, and they don't disappoint.
Oh, yes, another obvious con is the risks of the second surgery. Relatively off- topic, but my second CI failed (internal failure) after a few years, it was part of a dodgy batch, apparently. I had to have my third CI surgery.
All the best for you