Another "which seat to get?" post

DD is 4 y/o, 45lbs. She is on the top slots of her MA with about an inch or more to grow in harness height, but complains about her shoulders being snug. She is in the 2nd from the top slots of her GN with about 1/2 inch to those slots. She really likes the GN. I have the nauti installed in the suburban and have had the MA in the commuter car. We will be in the car at least an hour/day beginning on the 10th. I have to get her something else to ride in for her comfort and my sanity.
Do I
1) buy another Gn? I know the nauti installs in that spot and I know she likes it.
My other option and the one I am leaning toward is a convertible. I like the option of having a seat DS can ride in RFing in a pinch. I have been leaning toward the radian as it seems to the best of all worlds. DD will go to a booster in less than 2 years and I think a radian would last her that long, but I am really worried about the install. There are not knowledgeable techs here to help me out if it is difficult. I also am considering the TF, just because I like the monet and would trade for the sporty blue when she outgrows the seat and ds needs it. But getting the pink cover defeats the whole purpose of getting a seat for JIC.
I really need help making this decision. I have the money to buy but can't make up my mind. Should I get a GN, TF, or RN?
Thanks
Amanda

If you really think needing to transport DS JIC will happen, get the Radian. What car do you have? Maybe people here can tell you how it installs in that car (easily, poorly, tricks, etc.).

If JIC is a very rare probability go for the Nautilus and hope JIC doesn't happen (or get a different seat for JIC).