AlwaysOn AG and Cross-Database/Server Transactions
Is there a way to live with this limitation?


As of now, no not in a supported manner (I won't reference the link, as you have already done that in your original question).  There are potential inconsistencies that can arise from this configuration.  With that being said, there will be no hard enforcement on this, so you will not be prevented from the implementation.  But with the possible inconsistent pitfalls that may arise, I wouldn't and couldn't make the recommendation to go forward with AGs and distributed transactions.


  What do you guys do who use AG and have cross-database and cross-server transactions?


Currently, not implement AGs in this type of environment.