Our problem with this is that it doesn't take into account services which are quoted and invoiced in a foreign currency.

Example:  We are based in Australia, and so our home currency is Australian Dollars (AUD).  We have clients in the UK, working in UK Pounds (UKP).  We have a standard service item which their quoted price is, say, 1000 UKP, which they purchase every month.

At the time the service was created it converted the original 1000 UKP to 1875 AUD.  However, each month that varies, so charging 1875 AUD 2 months later might result in an invoice for 990 UKP, or 1100 UKP, depending on currency fluctuations.

That means that every month, despite this being a recurring transaction, we have to manually adjust the invoice to re-establist the price as 1000 UKP.

Obviously, we also cannot set this up as a recurring transaction since each month the customer would get charged a random price rather than the agreed 1000 UKP.

I think it's a bit of a stretch to say that QBO is fit for multi-currency use.  It offers a very limited currency conversion feature, but if transactions cannot truly be made in either currency without manual intervention it is not a true multi-currency system.