I carry my 15" MBP 2 miles to university and back, it's never bothered me with it's extra heft. I don't regret it in the slightest.
Me either. Its not very noticeable at all.
I have the 13, love the portability, but have regretted that i didnt get a 15 from day one for the screen real estate to play with
I did and had to do something about it - that's why I sold my 13" to get the 15". But then again, for me it was more about the horsepower the i7 offers than the screen size.