I have flown both...

It is a complex decision!. I own a 12s and flew BV's 10s. I was very impressed with the 10s performance and flight times. It does everything you want
But for me, I really like the extra power of the 12s. It is a racer!

I think It is mostly a money issue. I do not find the extra weight significant in performance, and with a Powerlab 8 running on 24 volts, you can charge your 3 batts in parallel at 2c in 25 minutes

Net, if you can spend the extra money (which I agree, it is significant), i would go 12, but it all depends on how much you want to spend and your flying style. The electra is extremely capable on 10s.

Hope i did not confuse you more