second thoughts on booster use

I have been following another post regarding booster seat use for a 4yo and now I'm having serious second thoughts. I have a 37# 4 1/2 yo that I just purchased a Compass B510 for to use in our Volvo s60. She is in a Regent in our main car, but I, too was tired of transferring seats(have a MA in the Volvo full-time for little sister, so I would pull her other MA out of Yukon, readjust straps and install in car when needed for 4yo). I sold my RA, bad decision! I figured since 4yo DD is going to be in preschool and may be picked up by grandparents, the booster would be a good choice, since I could fold it and have it in the trunk when not needed and it would be easy for others to pick her up from school.
I'm really not one to sacrifice safety for convenience, but after reading the other thread, I think that is what I'm doing. I guess I thought she'd still be safe, but it sounds like she's still too little for a booster. Plus, when we took it on a "test-drive" she fell asleep and her head was practically in her lap, which I didn't like at all. I realize accidents can happen on short trips, too, so even if its an occasional use seat, she still may not be safe.
Do you think I should buy another RA for 2yo DD and stick with the MA for 4yo? Is the vest that was mentioned in the other post compatible with the Compass booster? I have a Scenera for my mom's car but I'm not wild about it. Suggestions? Thanks!

I would keep your 2yo in the Marathon and get a Graco Nautilus for the 4yo, personally. I don't have one, though, so I don't know how easy they are to install. I got a Regent for my 4.5 year old b/c I wasn't comfortable w/ a booster for him yet, either. I hope others who know more will chime in.

The Nautilus is super easy to use and install. The 86Y harness is good, but it seems far more complicated than just getting a harnessed seat in the first place. It's great for kids who need or want the harness who are over the weight or height limits.

For *occasional* use I'd be ok with a 4.5 year old in a booster. Piper rode in a booster occasionally at that age when I had knee surgery and required people to drive us around. But no way would I have used it for a main seat, or even a seat that was going to be used more than occasionally.

Wendy

I have a Compass B510 for my 38 lb almost 5 yo dd. Its for Grandma's car and occasional trips. She rode pretty well in it.

To prevent head from sinking so far down you could lock the seatbelt maybe.

I have a turbobooster for occasional use for my 4.5 year old. It's mainly for my mom to use when she has my son once or twice a month. Her van doesn't have locking seatbelts and she cannot install a carseat correctly to save her life. I leave the booster at daycare when she picks him up. I'd rather my son be in a booster used properly than a carseat that is installed wrong.

If you're looking for a new seat, I'd go with the graco nautilus. It's very easy to install. Plus I really like the cupholder.

I agree, get the nautilus! Its a very user-friendly seat (my 5y/o can buckle/unbuckle herself!)

I would get the nautilus too. For occasional use by grandparents it could be used as a booster.

The Nautilus is super easy to install!!! Serioulsy it take me maybe 60 seconds to get it in my car, good and snug.

Okay, it sounds like most would be comfortable using the Compass for occasional use, which is what it will be. The car it will be in is the one my DH and I drive to work. We have 5 children, so I really wanted a seat that wouldn't stay in the car, but could be put in easily if needed. I like the Nautilus idea, but sometimes I will drop my older DDs off at soccer on my way to work and then I'd have to pull the seat out and find a place to store it. The booster folds, so it will fit nicely in the trunk when not used (DH's golf clubs live in the trunk, so not much space!). I feel better knowing that most would be okay with a child her age taking short trips in a booster. I think I'll give it a try and see how it works out. Thanks to everyone for your responses!