RFing to HBB?

My LO's are only 3 months and 24 months so I don't know why I am even worrying about this now, but I'm curious anyway. So, my LOs will be rfing until the limits of their seats (CA for DD#1 and probably a RN 65 for DD#2 when we are ready to transition her to a rfing convertible.

Anyway, my question is:
Is it safe for a child at 40 lbs (I don't know how old kids typically are at 40 lbs.) to go from rfing to a HBB booster like the Parkway or Oobr or something similar? I totally get the benefits of ERF, but I know some people, I think Adventuredad (?), go from rfing to booster instead of EH. So, basically, I'm wondering what the benefits of EH are as opposed to a HBB (assuming both are used properly and the child is mature enough to sit well etc.)?
Thanks, and don't worry, my kids won't be ffing until 40lbs. or longer if new seats come out by then

There was just a thread about this.

http://www.car-seat.org/showthread.php?t=93995

The average child is 4 years at 40 pounds. And no, I wouldn't consider that an acceptable age to be in a high back booster full time.

AD's logic (and that of many Scandinavians) is that it's better for the head to move more during a collision and therefore reduce the stresses on the neck. The logic of many Americans is that it's better to have the body more contained and therefore the head and neck move less overall. So we do five point harnessed forward facing seat and they don't, they go from rear facing to boosters.

After age six I don't know that there's a safety advantage to a harness over a booster. Unless you have a small child or the wrong booster and you're looking at a submarining issue, or you have a child who just isn't booster ready. But until the skeleton is ossified I'd use a harness to prevent internal decapitation. A study out of Sweden showed that four and five year olds were still at a much higher risk for neck injuries in boosters than rear facing (remember, no harnessed forward facing seats for them to use to compare to). I've heard several stories of four year olds in boosters who sustained neck injuries that could have been avoidable if they'd been harnessed. Yes, their head and neck moved together, but both moved too far and caused damage.

Also, while you have some very very tall seats and likely your kids will make it to 40 pounds rear facing, if they're very lightweight they may max out the height before the weight (unlikely, my daughter is teeny tiny and would have hit 40 pounds in both before height, but still, it is a possibility) and so if you have a four year old who has maxed out the height but is only 32 pounds, then a booster isn't an option.

And like you said, it so depends on what seats are available to us in the next several years. This year has been very exciting for CPS. Hopefully the next couple of years will bring more exciting seats.

Wendy

Ditto to what Wendy said. If you have a smaller, lighter child they may be able to make it until booster age in a RFing seat depending on the seat and whats out in the next few years (age 5-6). My own kids most likely could get to booster age just fine in a RFing seat, I just choose to turn them around age 4. The majority of 5-6 year olds probably won't be too comfy still RFing in any current American seat. If they change the design in a few years, that will probably change. But I can barely cram my little 4 year old in most RFing seats anymore even though she has plenty of room height wise. The Radian's pretty much the only one she's remotely comfortable in and even that's iffy.

If they hit 40 lbs at age 4, then probably it's best to harness forward facing a bit longer.

oops, sorry I should have looked more before I posted thanks for the info