I've played both EU and US servers and tried even with a VPN client. I play on an ADSL2+ TPG link, consistent 12mb down and about 1mb up. I have a router with QOS and placed diablo on the highest priority. I applied the Leatrix Latency fix and also tried to play through wireless and cable without much improvement. My line have no Jitter and I see no drop in quality during the day or night.
At most times when Bliz is good I can play at 260ms lag, but during a 2-3 hour play you can be sure it will jump up to 450ms or higher, depending on how bad or congested their servers are.
At work we have a dark fiber 10mb link with very high quality - we test some serious international websites on this link. Playing on this link is exactly the same as my home link, no improvement in lag.
At most times when playing on 260ms I still feel the game is choppy and with a DH running and shooting still result in rubber-banding.
It is obvious that Bliz will not give us servers and it is guaranteed for Australian Internet "NOT TO" improve either.
I feel the issue is Bliz's to resolve by doing one of three things: (Blizzard, you can add anything else if you feel you have a solution)
1. Have the client do more without connecting back to the Bliz central hub. If they feel they want to give us a free standing client - go for it.
2. Fix your servers to allow more bandwidth, either allow priority for remote countries - so we can play, allowing 250ms consistently. (Not sure we can get it faster than this)
3. Provide us with some kind of resolution, anything...
I challenge Blizzard to surprise me and provide us with their thoughts.