We had our fisrt longish journey yesterday, and 6yo and 4 yo both fell asleep. Even though the kidfix is supposed to recline, it really doesn't recline that much. If your DC is 15kg, but not very tall I would stick with a reclining 5 point harness for as long as possible.
Every thing else about the Kidfix seems great, though.
Thanks LS. Did your children manage to fit into the 5 point seat until they were 4?
I have the Britax one with the foot prop at the mo but DS is quite tall and finding it a bit of a squeeze. I always assumed he's hit 15kg around 3 so we could move on but was a bit surprised to see the Kidfix recommended for 4-12 years on the Britax website (I'm sure the predecessor wasn't). Really don't want to have to find another one to bridge the gap as I like Britax and the ISOFIX system. They should do the Evolva 1-2-3 as an ISOFIX (but I suppose that would lose them money!).