Gera,
I used to do this; I still use the live version of topaz. So if anything breaks, the next reboot will bring me back to where I was. Depending on the app I am trying out, sooner or later, the fragile ecosystem will break if I continue to use squeeze.
There is an old post somewhere here from Thana that advises against using squeeze. It's like voiding the warranty. If you are working on an installed Elive, and it breaks, you get to keep the pieces. Unless you've made a good backup recently.
Plus I think debian has updated recently.