A new button for in-lobby auto balancing of two teams is now on FAF Develop. When pressed, it balances players into two evenly-sized teams. It does not balance the same way as opti does. It tries to balance both teams' base ratings and uncertainties (grayness), with more weight given to balancing the base ratings. Here is the relevant PR.
Note that the current balance calculations used in this are tentative and may be adjusted in the future.
Also note that the estimated balance percent currently provided in the lobby uses different calculations from this and is not perfect either.
The purpose of this thread is to increase awareness of this new feature, encourage trying it out, and get feedback. Constructive thoughts on the balancing it provides (what you like, what it balances well, what it should balance better, etc) are welcome.
I am also considering additional changes to how this autobalances that would theoretically involve further increasing the balancing quality at the cost of lowering the autobalancing speed (ie: making it less likely for the 2 highest-rated players to be on the same team, with a slightly longer processing time). So, thoughts on whether or not that sort of thing is desired are also welcome.