My daughter is 5.5, just under 50 lbs, 43 inches tall. She's still in a convertible - Britax Marathon - and we have some time on the weight, but we've been looking at moving her into a booster. I've been researching all the blogs and reading all the previous posts and would love to hear if there a benefit to getting a 5 pt harness booster, if we still have the convertible? Seems like there isn't and may not be worth the added cost but I'm not sure if I'm missing anything. Also, please recommend yours. I do want it to have a LATCH system and high back that can eventually convert to a non-back. Thanks!