LMDE can be a great choice, especially as it can be faster than the Linux Mint main edition, but you should be aware of what it means that it is a rolling release: that with each update pack you can get new versions of the software you have installed. Not just security updates or bugfixes as with the Linux Mint main edition, but also new features (even complete changes to your OS, as with UP#4 introducing Gnome 3). And yes, possibly breakage of your installation (hence, I imagine, Clonezilla as a suggestion). It can be somewhat more work to get working as you want, but there are a lot of satisfied users.
In your case however, I'd suggest wait a month or two for LM13 to arrive, and try that. You like it? Go with that and not worry about much else for 5 years