I had my hand on a Nikon full-frame DSLR kitted with tons of stuff, and a super telephoto lens, complete with lens hood.
It dwarfs my NEX by a huge margin, and you need to be VERY steady with that, unlike the NEX which can be held with one hand. The weight is out of hand, too. :P It needs its own bag (it's from someone else in the same group), while I can stuff mine in my usual without caring.
Even the viewfinder is very uncomfortable compared to the bright LCD :3 Not to mention all the things you can do with a digital display