Questions about booster readiness and best boosters

Hi!

I have a little girl who is turning 5 this week and have a few questions about the next seat I should purchase for her, as well as her readiness for booster.

She is a little small for her age, just hitting the 40 lbs mark now (more like 39lbs, but depending if she had a big meal, could be 40 LOL). She is just at 40 inches.

1) I have been looking at the Frontier and the Nautilus seats. I would prefer to keep her harnessed and those seats seem like very good options, seeing as they would convert to a booster when the time comes. Any preference between the two? I like that the Frontier is latchable...
-Which one will she be able to use longer in harnessed mode?
-When would she be ready for booster mode? She is very mature for her age, and I don't think she would move the seatbelf or not sit still... but she does tend to fall asleep on longer drives...

2) I am wondering if you feel she would be ready for a booster, for very rare use. My in-laws bought her a turbobooster for their vehicle, and at first I was very quick to say that she wouldn't be riding in it for a while, but I am starting to doubt my thoughts! I totally trust your opinions on the matter and am wondering if I'm not being a little bit unreasonable? When I say rare use, I mean picking her up from daycare (5 minute drive to and from their house) maybe every couple of months, not on long drives, no highway...

3) Which of these seats perform better/would be a safer choice as a booster? Nautilus, Frontier, Monterey?

thanks so much for your thoughts!
My little girl thanks you too
Karine

1. - The Frontier and Nautilus have very much the same top harness height, so they will last about the same as a harnessed seat.
- She could probably be ready for a booster in the next year or two. It depends on maturity, like you said.

2. - 5 years is a good age for booster training - short trips in a booster, making sure that she sits properly the whole time.

3. - Some people don't like the Nautilus as a booster. It doesn't go as high as the Frontier. Of the three, the Frontier goes the highest. But the Nautilus becomes a backless booster as well (I think the Monterey may as well, I'm not totally sure). Right now I'm thinking about the Monterey for my little girl once she's ready for a booster. But she probably won't hit 40 lbs for another 4 years, so I got some time to think about it