I recently used amazon.com to buy BF4+premium+PS4 upgrade (paid $100 instead of about $180 it is in my currency). Works fine on PS3 so far. I used a Microsoft store billing address ;-) However, I'm holding off with any more purchases until I'm sure this will work:
1. Buy a game on US account
2. Switch to EU account
3. Connect with Vita via remote play and play the game.
I have no idea if the bolded part will work. Of course my Vita is tied to my EU account and I can't switch. I'd have no problem with buying another memory card for the US account but the switching process it awkward.
If it doesn't work, I'll be a sad panda.