MySQL Master-Master Replication on 2 servers
This is an interesting approach!

As you rightly noted, that bug report was wrong a long while ago and didn't get traction. 

As you mentioned you have developers able to help, I would suggest you do a quick evaluation to identify if the install procedure (without installing sample data) breaks still with an autoincrement >1

Obviously, in a separate install that you might end up trashing.

in your install/index.php line 1007 or so alter  requireMySQLAutoIncrementIncrementOne so it's first line is 

return; // bypass the test, the sky might fall, but at least we'll know how exactly.


I think the general plan for inclusion of a new feature is: if you do the work of identifying the issue and code the fix(or fund the work if needed), it's likely to be accepted ;) 

Assuming that it doesn't have any impact for "normal" users that have an increment of 1, I personally would want to try (or at least master-slave for a starting point)