I strongly avoid playing that game, for my "primary devices". For devices that I just tinker with, or are just laying around and I don't care if I can't take the time to "make it work" for a few weeks, maybe. But, otherwise:

Maemo, Ubuntu, or Android on vendor supported hardware: Many Plusses

Legal Mac OS X on Apple hw: Some Plusses

Linux other than Maemo, Ubuntu, or Android on vendor supported hw: Neutral

Android, Legal Mac OS X*, Legal Maemo*, or Linux on non-vendor/Apple supported hardware: Some Minuses

Non-Legal Mac OS X, non-Legal Maemo on non-vendor supported hardware: MANY Minuses

Windows (any flavor, on any hardware): TOO MANY Minues


(* such as: ripping out the motherboard of a mac mini or macbook air, and putting into another device that has the case profile you want -- it's legal, but very unsupported; I haven't actually tried it, but I've considered it for a tinkering project ... and as I write this, I suppose I should consider similar possibilities with the motherboard in my N810)

(in this case, "legal" means "not pirated, not in violation of the software vendor's license")