Personally I've always wondered by the 17" is so popular. No knock on the current owners and prospective buyers.
I've read enough complaints from prior owners about trying to use it in flights (too big) and lugging it around (it gets heavy and cumbersome).
Like everything else its a personal preference and many people swear by the 17" (or is it swearing at)
It is *not* heavy. It's 6.6 freaking pounds. If you can't carry that 24/7 you have a health problem. I'm 48, out of shape, and do not have a problem carry the 17" mbp around all day.
Tom