Funny you should say that given you're the one mostly looking at BtcChina and claiming all the other exchanges have to adapt to their low price.
There cannot remain such discrepancies in price. Since btcchina cannot follow price on other exchanger. Chinese and their arbers will arb to take the gift of an insta profit.
Price will level out, with max 5% difference, to the downside on other exchange and upside on btcchina. So around 8-10% less in the coming days on stamp irrespective of coming price fluctuations.
What have you been watching this whole past month?
We've had 20% disparities one way or the other all along, every single day.
I think a lot of people here are used to the concept of arbitrage closing gaps to almost 0; but the truth is that can only happen on almost perfect markets, with standardized rules, and level playing fields. This is certainly not the case for Bitcoin exchanges.
Every exchange we got relies on different ways to get fiat in/out with varying costs, different trading fees, great volume disparities, different international laws and barriers. All of these factors affect and are accounted for in each exchange's current price. This, plus the fact that things move very fast in bitcoin times (which is a nicer way of saying we got the bare minimum short-term stability, if at all), prevents the arbitragers from being able to effectively close that gap. Arbitrage here is more about making the most use of those disparities when they appear, sorta riding them; but it does not by itself imply the gap will be be closed.