finn's is on the side, his bucket seat was too. i feel safest using the latch system and you can only use those on the side. also, the best fit is wherever is installs the best. they recommend the middle but for most people the best fit is on the sides.
he seems so much more comfortable in this seat and i can tell he likes being higher up and able to see out the windows.
as for the bulky straps, you can remove the crotch pad and the shoulder pads (those are just for comfort), you can also remove the plastic/rubbery strap cover things but keep them somewhere safe because you do need to use them when she's forward facing. i left all those on though, i especially like the shoulder pads because the straps can't rub on his neck.
what do you drive? we have a small sedan and we didn't have to push the passenger seat forward at all. i know we have different seats (ours is the marathon) but i don't think there's much of a difference in size if there is one at all. in fact, the britax takes up less room than his bucket seat did.