It usually includes updates (or myself by mistake? not sure) making my system so broken that I have to reinstall and start again from scratch.
This year I thought I'd try with the Pro after the MacBook Air wasn't upgraded with retina, but if I have to spend almost EUR 2,000 and have faulty hardware and a broken OS that shows my password in clear text, might as well spend 1/3 to get a just-as-good laptop with elementary OS on it.
I hear that a lot, but I always wonder what distro people are using or what they do to their machines or what hardware they have etc.
My current laptop at home has been getting every 6 monthly Ubuntu in-place upgrade since 13.04 and hasn't had an issue. Same with the kids second hand laptops. But I choose Thinkpads and make sure I always get Intel graphics and wifi chipsets for compatibility.
Based on my colleagues experiences though - I don't have anywhere as much upgrade confidence at work with my Macbook Pro though (still on El Capitan).