I totally agree with ergonomics and back. I try to stay active physically, stand and walk a lot, to compensate to some extent. So far so good for about 13 years on laptops, though I'm relatively young so maybe that's just my body tolerating the negative sides.

Though sometimes I put a box on the table and put the laptop on top, effectively turning into a standing desk a work a few hours like that. It really helps not to be sitting the whole day.