I own the new version of the Chorus 726. I auditioned the 726V and 826W, and read up on Focal quite a bit.
My understanding is that the only difference between the upper end 700V and 800V is the construction. The drivers are the same. However, in your case, you'll be moving to a larger driver, so you'll have more output. Do you need that? Personally I like the look of the 816V over the 714V, so that may also be a consideration for you. Also, I have heard from some people that the 800 series center is better than the 700 series, so if you are going to upgrade that also you will probably end up with an overall better system.
The big changes come with moving up to the W series as the drivers are completely different from any of the V series.