I had a shop "accidentally" charge my foreign visa card in USD today despite my making it very clear that I wanted to be charged in baht and their insistance that it would be. I had them cancel it and rerun it in baht. This means I got to see the very clear difference on my pending transactions. I also took a screenshot of transferwise and the rate reported by google at the same time for comparison. I thought the data might interest some people here. Really can't beat just using a credit card in terms of exchange efficiency, assuming you can find a bank that doesn't markup the rates from visa.