What if I install Yosemite on a new drive and then clone it?

[brainstormer]

Ok, I have decided to upgrade. But I have a ton of things on my working drive, a lot of crucial projects that I don't want to risk losing.

Also the current size if the disk is huge and making a backup might not be feasible a.t.m.

I have a spare drive though, which I use to clone my main Mac drive (the entire OS minus the folder that contains my work files/projects). So I am thinking, what if I upgrade Yosemite on this spare drive, and then use the Carbon Copy Cloner to clone it to my existing (main) drive with the option to not delete any other files on? Will that work?

 

[smcpipint]

Will work fine, I do that regularly. But you will probably need to manually install the boot loader on the cloned drive; I don't think that CCC does boot loaders. At least it didn't when I last tried.