Britax Marathon Review

I purchased the Britax Marathon for my first baby after I heard how strong and safe it was.  I used to use the Graco infant carrier so when I received the Britax Marathon, I was surprised at how big and bulky it was.  I guess it's because it's very strong but the height of it was too high, everytime I put my baby in I have to be careful not to hit his head on the roof the the car ( which I did few times...ouch...poor baby).  I am now considering changing the car seat to something that wont take up so much space and does not sit so high in the seat.  I do appreciate the dependability the Britax Marathon offers and the design is very nice as well.  If I was to change it, I would make it less bulky so that the back seat can seat more than one person even with the carseat in it.  Right now I can only seat one person with this huge thing taking up so much space back there.  It is too expensive and the namesake is not worth such high price tag.  If I was more educated with the subject I would have gone for something less pricier and bulky.