Recommended Convertible Seats harness past 40lbs
Here are some convertible seats that I usually recommend based on how long you can keep your child harnessed...the longer the better!!!
1--Britax Marathon/Boulevard/Decathlon. These seats will RF to 35lbs. They will FF, IN A HARNESS to 65lbs. These seats run $200-$300. There are small differences between them. The Marathon is the basic model of the 65lb convertibles with a lift lever harness release--with quite a few different covers to choose from! The Boulevard has "wings" called True Side Impact Protection. It also has a harness adjustor knob that will move the harness without having to uninstall the seat. It is about 1/2" shorter than the Marathon and the Decathlon. The Decathlon has extra padding--the infant insert--and a push button harness release and 3 position crotch buckle settings. http://www.britaxusa.com/
2--Evenflo Triumph ADVANCE--harness to 35lbs RFing and 50lbs FFing. It has the infinite harness adjustor (no slots), so you can easily lift two red tabs and move them. This seat runs $129-$159, depending on which model. The higher end model, the premier, has more padding. http://www.toysrus.com/search/index.jsp?kwCatId=&kw=evenflo%20triumph%20advance&origkw=evenflo%20triumph%20advance&f=Taxonomy/TRUS/2255957&sr=1
3--Compass TrueFit--- It RF to 35lbs (with the headrest on and 22lbs without the headrest on) and FF to 65lbs. It seems to be competitive to Britax convertibles. Runs about $179-$189. They have several covers available. http://www.amazon.com/Compass-True-Convertible-Seat-Monet/dp/B000YBIL4W/ref=pd_bbs_1?ie=UTF8&s=baby-products&qid=1200280582&sr=8-1
4--Sunshine Kids Radian 65 or 80--These seats will RF to 35lbs and FF to either 65lbs or 80lbs, depending on the seat. These are the narrowest seats on the market, but have the highest incompatability with vehicles due to the low FF belt path. Runs $180-$300. www.skjp.com
5--Recaro Signo or Como--RF to 35lbs and FF to 70lbs. These seats come in a variety of microfiber covers. They have true side impact protection, but the Como is VERY oddly shaped. The shoulder area is 9" of space and the butt area is 11" of space, so unless you have a tall beanpole, this seat may be awkward for some children. I haven't played with the Signo, so I don't know the measurements off the top of my head. They are supposed to go to 59 or 60" tall---I dont' see it. Runs $250. http://www.recaro.com/index.php?id=3312&L=2
Most of these seats have a higher sticker price on them, BUT the seats that have the 40lbs harness limits, that are less expensive, usually only harness the child to maybe age 3-4. AT that age, MOST children are not ready to go into a booster. Bare minimum safety standards say that you can put a 4 year old AND 40lbs child in one, BUT being in a harness is MUCH safer....not just for children, but adults as well.
****Just remember that the right seat for you is one that your child fits in, it fits your vehicle AND you use it correctly each and every time.****