A guildmate brought to my attention a concern about one of the achievement rewards coming in the next patch.
The Safari Hat will be the reward for defeating 45 Master Pet Tamers (Taming the World) in 5.1. This item is BoA, which means it can only be mailed to toons on the same server (cross faction included) and not across realms.
For players that have toons spanning multiple servers, this is a problem since only one group of toons on one server would have access to the hat.
However, Mumper clarified on Twitter that all toons on an eligible account will receive the Safari Hat. All characters, regardless of server, will get the hat after completing the achievement.
So no worries if you enjoy leveling and Pet Battling on one of your toons on one server, while your characters on another server are reserved for doing other things. You'll have access to the pet experience boost on both servers.
I guess that means more Pet Battling for all, including alts! :D