I'd read a lot of good things about the fee free Wizard mastercard for international purchases, so decided to try it out last week in Bali.
I also have a Citibank visa c/card, and alternated my purchases using one of each over there (told my husband I needed to make a lot of purchases, just so I could have a good sample size!)
Have compared my statements and Wizard does live up to the hype. Conversation rate on Wizard was on average 8600 rph to the AUD, compared to 8300 with Citibank - so a 3.4% savings to use Wizard over Citibank.
Of course with Citibank visa I also earn frequent flyer points, so I now have to decide if points are worth 3.4% to me.