is it worth to flash all s9 to awesome miner's firmware?
According to awesomeminer it gives a boost in hashrate if you flash them with awesomeminer firmware. Never had experienced using their firmware I only use their free software for monitoring.
Why not, try to flash a few of your units with their firmware and test for yourself.
And then you can revert it back to the original firmware if you don't like the little improvement. The improvement is 10% hashrate increased and improve power efficiency and you can manually overclock and underclock the unit.