Hi Quickstatus,
I'm in the same boat. I have used the QF Cash card for my daughters, with great success. Both of them were over 16, which I think is the minimum age and we had no problems.
We went to USA, no problems accessing cash through ATMs or using as a debit card in stores/
My son is only 15 and soon travelling alone for a sport trip, and we are having trouble finding a card he can use. Looking forward to any suggestions!