Focal Electra and Focal Sopra

The Focal Electra center (CC1008BE) is the same exact product as the Sopra center. The only difference is the cnc aluminum center piece. 

I am not a pro in this area, but I have focal electras, chorus, and profiles, I also have an electrical engineering background, and for what I was able to compare between profile, Electra, and Sopra center beside the obvious, electras and Sopras have a beryllium tweeter but also the crossover is a bit more advanced, I would suggest you research about improving the crossover parts or just leaving it as is because they are basically identical, obviously there is a change the actual construction of the drivers are a tiny bit different but visually comparing those I would say not likely if you later want to sell your Electra center, I am in the market.

Depends what you want to get out of it.

The question really is whether you hear a mismatch as sound travels from L to C to R.  If it sounds completely seamless, then no.