Been lurking on SF for two years and finally decided to pull the trigger on a 256 or 257. I've looked through almost every page on this thread and still can't decide, and I'm in London where I can't seem to find anywhere that stocks them. If anyone could help me out here: I'm looking to hold a 13" MacBook, a charger, and an inch or two (usually two) of A4 notes. Maybe a small water bottle. Would the 256 be sufficient? I'll be carrying an iPad and about an inch or paper on my off days, so I don't want the 257 to be flapping around empty.