Berg go carts.

jlm29

Not sure if I should post this here or in toys and games, so mods, move if appropriate!
I have a boy who's just gone 5, and tall for his age. I'm looking to buy him a go kart for Christmas. The berg ones look great, and seem to get great reviews everywhere. I'm a bit puzzled regarding the best size though. The berg buddy are for age 3-8, and the next one are for age 5+, but look massive.
Is the buddy a waste of money? I don't want to buy the smaller one if he will have it outgrown quickly, but I don't want to buy the bigger one if he won't be able to manage it properly straight away.
Anyone any advice? There's no shop local enough to go and look (the local retailer orders them in, doesn't keep a stock).