Other Slim Car Seats Besides Radian?

[not_telling]

We need to purchase new seats for my 4 yr old so his sister can move out of her bucket and into his current seats.  We were all set to get Radians, knowing it would cover him now through booster.  However, someone I know told me that she has friends who do work as car seat inspectors and they have said that the Radian is actually not a great booster because the seatbelt positioning is not the greatest.  Which has me wondering if we should be thinking about either:

1) getting another kind of all-in-one seat

2) getting a radian (or other FF seat) and then purchasing boosters when he gets to that point.

Whatever we get, we'd prefer it to have a slender profile.

Thoughts?

[chickabiddy]

It's true that the Radians do not make excellent boosters, and kids will outgrow them by height before they can safely ride without boosters.

I would generally not recommend a convertible seat for a child who is already forward-facing.  It's a waste of money to pay for rear-facing capability and never use it.  I would recommend a combination harness-to-booster seat.  The Evenflo SecureKid is relatively narrow and makes a decent booster.  All you'll need after that is a backless booster, and those are under $20.
 

[DahliaRW]

The other question would be when do your ds's convertible seats expire?

[brigala]

None of the forward-facing combo seats (the ones that convert to decent boosters) are anywhere near as slender as the Radian. A lot of them do tend to be lower-profile than your average convertible, though.

If a really narrow car seat is a high priority, then a Radian (or a Foonf) is your best bet. 

If you have room for a 19" wide car seat, then a forward facing combination seat is a better option for long-term economy. The longest-lasting one on the market (both as a harnessed seat and as a booster) is the Britax Frontier 85. Other options include the Evenflo Secure Kid 300/400 or the Graco Nautilus/Argos. They're all within half an inch or so of each other in terms of width, though different ones may fit differently in your vehicle or against your other car seats.