Just a little warning for all considering to transfer a character from one account to another that you will loose your AP mounts and all blizzard shop mounts and pets.
I just transfered one character from my first account (with all those mounts and pets) to my second account on the SAME battle net account. And made afterwards a guild transer.
When logging in with a character on my first account it fell from the sky, because the mount was gone ... Checking on the other account: Also no mounts and pets there (missing 3 mounts from the pet shop, the AP pass mount and one pet from the shop). So they are gone from BOTH.
After checking the forums I created another char on the first account and received them in my mailbox, BUT you can only learn the mounts when you are level 20 and they are soulbound.
So I contacted a GM and got a really "nice" answer.
Hi there ***!
This is a slight drawback of the new Battle.net Mounts system, but once the character is able to learn those mounts, you should have them available to that account entirely once more.
So to summarize: I paid for the mounts and pets, I paid 50 Euros for the transfers and now they tell me that I should level another char to 20 on a new server since all slots on my server are full to get my items back ...