My toddler is probably more in the 5.5 size than 6, but she can wear these just fine.  I think the structure of the toe, with the slight curl up, makes it a better fit than a flat 6, which would make her trip on the toe.  So, I think they will get a longer use, since they can be worn a little large.  That said, the velcro on the top is not the best.  My daughter (17 months) can easily pull it off, which would be good for older kids learning to put on their own shoes, but for my little one, it's kind of a drag because she's always taking them off in the car (which she does with all her shoes for whatever reason - when we are at home she wants them ON all the time).  I'm thinking about sewing a snap in there to stop this, though I am no seamstress.