I’ve dist-upgraded to testing/unstable:
antonm@antares:~$ cat /etc/debian_version testing/unstable
There were some problems during upgrade, I had to run aptitude dist-upgrade twice and tell it to update icewm manually, cause it complained about imlib1 dependency. Also, xkb-properties-capplet clears keyboard toggle key (that was a crutch and I really should set up it right way by configuring xkb directly). Everything else is working fine. I may conclude that was a painless upgrade.