Generally speaking a child will need a booster until approx 145cm tall. For DS1 this will not be until around 12yrs. Fir DS2 probably 9-10yrs.
Legally your child is required to sit in a booster until 7yrs of ge at a minimum. The 26kg seats are tested with 32kg test dummies so are fine to use beyond 26kgs. Also it is the adult belt actullly restraining your child.
I would not necessarily be running out to change unless I felt my child was not sitting well in their seat. SnS also have a new seat the Encore which is for older children officially.
Children should be in a booster until they pass the five step testhttp://childrestraints.co.nz/seatbelts.php
The 5 step test will tell if your child is big enough for the adult belt.
1. Does the child sit all the way back against the auto seat?
2. Do the child's knees bend comfortably at the edge of the auto seat?
3. Does the belt cross the shoulder between the neck and arm?
4. Is the lap belt as low as possible, touching the thighs?
5. Can the child stay seated like this for the whole trip?
If you answered "no" to any of these questions, your child needs a booster seat to make both the shoulder belt and the lap belt fit right for the best crash protection.Your child will be more comfortable, too!
5 Step Test
Edited by lsolaBella, 28 January 2013 - 12:01 PM.