well, tho i don use canon, i would still choose the f2.8, with newer camera popping out so often with better and better NR, one can easily bump the ISO to get pretty decent shutter for handheld without IS.
I use to find my 80-200 too heavy, but now when i handheld my other lens, i find them too light... -_-", but i still prefer light load when it comes to carrying gear around.