Question about Radian carseat size

We've got a really chubby bubba, who I'm pretty sure is going to hit 12kg plenty earlier than a year. So I wanted a carseat which can rear-face heavier than 12kg. I like the Radian, and it can fit in the car, which some can't (in the centre, it wouldn't fit behind one of the front seats).

What I want to know, has anyone ever had any trouble with them being too slim a fit? As in, baby growing out the sides? I'm hoping not... I think it's a good option otherwise

I think it should be ok. DD still has the body insert in hers (she's not a porkchop though ) but if I took that out there'd be heaps of room.

In reality, even though he's a very bonny baby, he'll likely slim out when he's walking so he's unlikely to have the same relative proportions then!!

Oh, and I'm pretty sure the radian can be used FF for kids up to about 6-8, so surely he'll stay slimmer than a 6 year old for some time yet

You might also find it will fit behind the seats when he's older and not needing to sleep in it cos you can sit it up straighter then.