Usage of the word concurrence
Is it correct to ask "Are we all in concurrence?" synonymously to "Are we all in agreement?"
"Are we all in concurrence?" is not incorrect, but unnecessarily wordy. I would suggest your synonym is better, but if the word "concur" is closer to your intended meaning, I would say "Do we concur?"
An important point to note is that "concurrence" implies "all" anyway, so leave "all" off.