So,

If I wanted to send say 50k gold to my horde toons (that are non-existant on staghelm) i'd normally have to filter it through the neutral AH and take a 20% tax...

In 5.0... consider this

Panderen do not choose a faction until level 10... 

what would stop me from sending him/her 50k and then choosing horde @ level 10

I'm guessing they will put a restriction into place, but if this is something you've ever thought about/wanted to do.. there is a thought

discuss

You can also transfer via neutral AH ITEMS that are similar (or more expensive on horde!) value, and then sell the items, and only take 5% instead of 15-20% cut.