Well, the erase time is 60 seconds or less, the Yosemite install time is comparable to the upgrade route and you can let Migration Assistant run while you are busy a couple hours doing something else, but to each his own.
Just the fact you have done several upgrades in lieu of a single clean install would scare me off from chancing another upgrade.
I am not a proponent of "clean installs", but without getting into that whole argument, what you are doing is not a clean install and is pretty much a big waste of time. A true clean install involves erasing the drive and reinstalling the OS, then
manually moving data and apps back.
The whole idea of a clean install is you get rid of cruft etc that is there from old installs. If you use Migration Assistant after a clean install it brings all that cruft back and completely defeats the purpose of a clean install.
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I'll be getting an Imac soon which has Mavericks soon. I can't wait for Yosemite and was wondering how easy it would be to go from Mavericks to Yosemite? Is it just the click of a few buttons or much more than that? I'm not to computer savy as you can tell with upgrading OS and stuff.
If it works like Mavericks and other upgrades (and it looks like it will) you will just go to the App Store and find Yosemite then click where is says free here and the OS will download to your drive and the installer will launch on its own. You will then get a screen that says something along the lines of "do you really really want to update to Yosemite"... you click yes and off you go. Very easy.
You should of course backup first just to be safe, but the Yosemite install will not erase your data. It just installs Yosemite right over top of Mavericks.