Being quite blunt and straight-forward with this reply. I have seen issues over and over with what you are pursuing:

1) What is your experience with windows clustering and SQL Server's Always On technologies? If they aren't very strong, you have a very high likelihood of things not going as you intend or functioning as you intend.

2) There are quite a number of windows patches and configurations to get right. Networking stack issues too. Specific SQL Server patches to apply.

3) Are you aware that reading from a secondary will modify PRIMARY ROWS adding a slot for the 14-byte version store pointer for read rows?? This leads to latching/locking/dirty pages/tlog activity (all of which also has to be sent over the wire via mirroring to be replayed on the secondary)? Oh, lets not forget the massive index fragmentation that can occur for those that use the default index fill factor of 0.

4) Do your myriad applications know how to properly interact with AGs? What will they do when the Primary gets yanked out from under them and moved to the other server?

5) Of particular concern is the various replications you have going on. Multiple forms of data synchronization can EASILY get TOTALLY HOSED UP. More i's to dot and t's to cross to have a chance of success.

6) Got any SQL Agent jobs (backups, maintenance, batch activities, etc.)? They need to be dealt with too because the database they hit may or may not be the primary on the given server.

7) Logins/users in the database? Another gotcha...