Update-
As an update to my last post, the Combi model will apparently NOT be released in the USA.
As for the other seats, I think they are all fine. All pass safety standards and testing. If they fit your child and vehicle well, they should all be very safe.
The Britax Super Elite is apparently catching up with demand quickly, so maybe prices and waiting lists will drop soon. Also, it will apparently be replaced by a very similar model with LATCH later this year. As you know the SE goes to 80 pounds with a harness, though you are required to use a tether to achieve that weight.
The Laptop is also a bit hard to find. It goes to 65 pounds. It had the advantage of being very light and relatively easy to install. Much like any backless booster, the disadvantage is that it provides no shell for side impact protection and no head support if your vehicle does not have headrests.
The Fisher Price Futura is a nice model that goes to 60 pounds in a harness. I own one. The only real disadvantages to this model are that it is hard to find, and that it isn't as comfortable as some other models. The 5-point version can be found at high prices on ebay. The overhead shield version still can be found here:
www.kbtoys.com/w/l/snb.ht...0&formMap=
EZ-On Harnesses are also reasonable solutions. See:
www.ezonpro.com/
Boosters are fine for children 40 pounds and over, though the children should be mature enough to remain seated in the seatbelt properly. No squirming off to the side or putting the shoulder belt behind their back.
Overhead shield carseats get a lot of undeserved criticism. Indeed, they are not recommended for newborns and infants because the shield harnesses tend not to fit small babies tight enough, and because the bar is at head level. They are just fine for older kids, and the Fisher Price Futura 20/60 overhead shield seat is a very good alternative for kids who are over 40 pounds but not quite ready to be in a seatbelt.
Good luck!
