We expect to distribute the load throughout the world when the game goes live and then use the darkfiber backbone to bring the clusters together, so latency should be less of an issue - as you'll be talking to your closest datacenter rather than pinging across to where our current playtest servers were (East Coast US, this time).
However, I'd be interested to know how you found the experience at 300ms. Did you notice any specific high-latency effects such as rubber-banding, teleportation etc? Would love to know.
Many thanks in advance,
EDIT: The tests that Maxxor did for Azure datacenters that were best for South Africa found the North Europe datacenter performed signifcantly better than the others. We'll automatically route you to the best/fastest datacenter, regardless.