Goldie - Combi Coccoro

I was just going to buy sunshine radians the other day for the narrow factor when you posted about these.  I wanted to see them in person but nowhere close to me has them in stock.  I can order them online but I wanted to ask you a couple of questions first if you don't mind.

 These go up to 40 inches and 40 pounds.  Do you feel like it is actually big enough to hold them that long?  I'm not sure how big Griffin is, but Carissa is 38 inches and 30 pounds which is pretty average for a 3 year old.  Could she comfortably ride in it?  She's in a Graco Nautilus now and has tons of room to grow.  If I get two of these seats I'll leave her in that and put the babies in these, but I want to make sure that more than likely they won't outgrow it in a year and it will last them until they are 40 inches - which will probably come before 40 pounds.  Thoughts, opinions, advice?