battery wise, there is a list here of everything that will foit without having to mod the car, i.e. they will fit between the battery posts.
http://www.uk-microrc.co.uk/forum/in...howtopic=16915
as for the pro's and cons, the availability of the batteries is the only major con, as a car it's great to drive, lots of setup's available and is pretty much good to go out of the box.
all you need to run is a set of better tyres and wheels, and some lipos.