i even removed the superdrive to make it more portable, but minus the super dive, it doesn't help significantly. i buy 2 chargers and put it on the office and my home so i don't have to put more weight in my bag. it's still heavy and not portable enough to carry it all day.
but, i can't replace it because i do tshirt graphic design and i really need the high resolution of the 17" mbp. i don't like working with external monitor, so i keep it as a better workhorse than 15" mbp.
if you just carry the mbp and magic mousr, it's not so bad, but if you carry these things like external drive, books etc, dang it's quite a burden.