The problem is that since oanda charge for the *use* of the API you will simply never get the kind of following that IB has or applications like brackettrader because you would pay for using it as well pay to buy it.
If oanda want to charge for using the api fine but they could get smarter on...
I read on trade2win that it is due to Brussels/european regulation that a FX broker must have an office/presence in the country that it services...
...so they need to open an office in the uk or close uk accounts.