The Cosco Alpha Omega only harnesses till 40# with quite low top
usuable harness slots (too many kids outgrow the harness before they're mature enough for any
booster) -- it then converts to a
booster, but one that lacks any side impact protection & kids also often outgrow this seat as a
booster too soon because of the short shell/frame.... The manufacutrer does an excellent job of tricking parents into thinking this is the "only" seat they'll ever need, but almost everyone who buys this seat ends up complaining later because they have to replace it: plus the top harness slot is only for
booster use! The manual does not make this issue clear enough so this seat has a high misuse rate

The 1 good thing about the AO is that it has the highest
RF limits on the market (however, many more seats do now, too, which cost less & are more user friendly).
The
Britax Regent keeps kids (who no longer fit
RF seats) safest the longest in the harness until 80# with the tallest top slots on the market. The
Regent's frame is also made of a stronger grade plastic in a double hollow shell design totally lined with energey absorbing foam.
There are also other options for keeping kids harnessed longer as listed at
www.cpsafety.org 