Earlier quoted context omitted.
Nicer GUI/UX is subjective. I find that the OS X GUI kills my productivity, but others may feel the opposite. Linux is highly configurable, at least, so you could get near-perfect OS X UI on a Linux machine. As for the hardware: I'm running Ubuntu on my MacBook Pro laptop, and it runs great. It boots much faster than my clean Yosemite install. In fact, Yosemite's performance was abysmal compared to Ubuntu.
This is a little off topic, but how is the battery life on your Macbook Pro when running Ubuntu? Last I looked Ubuntu ran fine, it just cut your battery life in half (actually both Windows and Ubuntu cut your battery life in half, when ran natively/bootcamp, and not via VM). So has that improved at all. It certainly hasn't on Windows on a Mac (the Apple bootcamp drivers are really unoptimised).
When I'm using my laptop (at a client, in a meeting, at the airport) I always have a power outlet, so my productivity is much more influenced by the OS than the battery life. Your lifestyle might be different.