Britax Frontier 85 - Rockwall,TX

I'm not sure what the Marathon is like (we had a Roundabout), but we found the Frontier to be an entirely different seat. I honestly don't like it much. It's massive, heavy and a royal pain to install. It sheds knuckles during install. So, basically we do everything within our power to never have to take the seat out and transfer it to another vehicle, even if it means our daughter has to stay home. Thankfully, we can convert it to a booster soon and I'm hoping my opinion of the seat changes then. Our daughter complains about the harness constantly -- although she did this with the Roundabout, so I think she just hates being strapped like a mummy to seats.

For what it's worth, I also hated the Graco Nautilus. That one couldn't install safely in our Honda Odyssey second row after two hours of trying to install it, so we returned it to the store. After my experience, I'm not a fan of the convertible/booster combo. I understand the need for them, but there's much room for improvement with future designs.

I was just looking at this seat the other day and I would have jumped on it if they'd had it when I bought my son his seat in 2008! This is exactly the seat I was looking for. The britax seat I have for my son will take him to 80lbs in a 5 point harness but it doesn't convert to the booster like this one will. This one seems like a lot of bang for the $.

It is difficult to install but feels very safe. My daughter doesn't complain about the harness, she moved from the marathon too. she loves the armrests and cupholders. She is almost never in another car so we don't take it out, and she's big so we have a highback booster for the rare instances she has to go in another car.

We've been using ours for a few months now, and we love it. It feels safe, and my son was thrilled to see that it comes with cup holders. I find that all car seats are a challenge to install properly without help, but we get help from the Irving Police Department (who ensure that you're able to install it yourself after they demonstrate for you).

Both of my kids are in a Britax Frontier. I do feel that they are very safe, but they are not easy to install like the Marathon.