How do you reinstall OS X on a Mountain Lion Mac?

I just got a new iMac. I have an older one running Mountain Lion for which I have Snow Leopard on disk. From what I can tell if my hard disk goes and I need to reinstall I can either:

1. Install Snow Leopard and upgrade to Mountain Lion via the app store
2. Install Mountain Lion remotely using a startup USB (though this requires I create the USB before my hard drive goes).

First of all, is this correct? Secondly, on my new iMac I could do either of the above. However, in theory I wouldn't necessarily have a copy of Snow Leopard or the USB stick. So, as far as Apple are concerned, if your hard drive goes and you don't have AppleCare, how are you supposed to get the latest version of OS X on there if it's only available from the App Store?

P.S. Is Snow Leopard safe to install on the newer Macs?

Thanks.

Your assumptions are correct for reinstall on your older Mac.

The new Mac has a recovery partition, this will download the OS and install. You have identified an issue that has me quite irritated with Apples new OS delivery philosophy. I believe you can download the install image, and make a USB as with purchased versions (I do not know, as I have machines that came prior to Lion, with Lion, and with Mountain Lion.. so I have purchased Mountain Lion from the App Store previously anyway.. and built a USB install).

You can not, in any way, install Snow Leopard on Macs that came out after it's withdrawal. Full stop.

Thanks, but isn't the recovery partition on your HD? In which case, you're screwed.

I agree with you, I think Apple have left some people in the lurch. I guess if you're out of AppleCare you'll have to either get a friend with Mountain Lion to create a USB or pay Apple to do it.

Yes, you are exactly correct. It is also why I dislike this method, but I also believe this will be more common moving forward.

Personally, I would see if I could download the installer from the App Store and make a USB bootable installer.

Lion DiskMaker

That is how to make the USB installer when you have Mountain Lion. Snow Leopard will not install on a new iMac. As a rule of thumb no going backwards for operating systems. You should be running a backup drive. A FW800 external drive cloned with SuperDuper or Carbon Copy Cloner will fill the bill. The external will be bootable if you have an emergency.

On the release of OS X.9, reportedly next month maybe at WWDC, if you update then use the Lion DiskMaker procedure.