I have a 6.5 year old son who weighs 43 lbs. and is 45" tall. I have him in a Britax Regent in our main car and he is on the second to the top strap right now. We use my DH's car occassionally and I need to get a booster seat for this car. Because this is a spare seat that isn't used much, I don't want to spend a lot of money but I want a booster seat that will last us many more years because in IL he has to be in a car seat until he's 59" and 80 lbs, which may be a long time from now based on how he eats. I'd like to buy this one seat and have it be our spare seat for him until he grows out of a car seat. I have a Frontier and Regent in our main car (DS2 is 3.5 years old) and a Regent as one spare seat for DS2. I was thinking a backless booster is my best option to get him through til he's 80 lbs. I've been looking at the Clek Olli and I'm leaning towards it because it is always latched to the car, but I am having a hard time justifying spending $90 for a backless booster when I see so many in the store for much less (I admit I know nothing about boosters options though). Your thoughts? TIA