A couple of MSR Reactor questions!

I'll be picking up an MSR Reactor very shortly. I know that the small gas canister will fit nicely inside of the 1L pot, but will the medium canister fit inside the 1.7L pot or will I still have to use a small?

Would you say the increased efficiency and capacity of the 1.7L pot is worth the small weight gain over the 1L pot? I'll probably buy both pots anyway but it would be interesting to know when I'd use one pot over the other.

Finally, are 80/20 screw top gas canisters available in France (specifically, Chamonix?) I've read a few things online that say that the Campingaz canisters are a lot more common over there.

Cheers!