I have a current Time Machine backup, but no bootable clone.
I can afford to be without the use of my computer for a few hours should things go horribly wrong and I need to restore it.
Just installing a clean version of Mountain Lion is always safer than installing onto a system with data and settings.By migrating the contents over to be sure all your third party apps are ready for the new OS.I'm considering charging ahead and installing Mountain Lion with just a Time Machine backup (in part so I can get up and answering ML questions on this site! Is this a reasonable course of action or incredibly stupid, and if so, what should I be doing instead?Personally, I would never feel safe with my data on just one backup disk.
I'm rarely an early adopter of new software, but I'm taking the plunge today and buying Mountain Lion.
I don't know if it will break anything important (I run a few rather obscure programs on my mid-2011 Macbook Air), nor if I will like it.