Sippy cups vs Rubbermaid juice boxes?

Neither of my children used a traditional sippy. They too did not understand the tipping part, plus they needed to suck so hard (with the non-drip valve in) to get anything to come out. I tried myself and I surely wouldn't want to work that hard! I used a juice box same as this (although your link doesn't work but I know what you are talking about) and experienced no downfall. When they were older the idea of using a regular cup was not a problem. Physically they were more ready for that. I switched them to a cup somewhere between 3-4 if I remember correctly. So from 1-3-ish they used the drink box.