I’m locking this one, in favour of keeping the discussion in a central topic.http://themeforest.net/forums/thread/new-badges/139831
The weight difference between a 15” and 17” isn’t an issue when I’m out and about, it’s entirely a marketing ploy. If it’s heavy your muscles will grow and get over it.
For me it wouldn’t just be the weight, though, but also the sheer size. A 13” Pro can be subtle and fit on a small lecture fold-out table, while a 15” or even a 17” generally tends to become a bit of a distraction. Then again, those really are beautiful machines