Good to hear that the Marathon's worked well for you.
Nice to see some Cyrillic script. For what its worth, I cycled across Russia, starting in Amsterdam and travelling to Vladivostok in 2007. I started with Marathon Plus tires on both front end rear. I replaced the rear tire with a Marathon XR approximately half way across (tread was wearing out, also had a flat I couldn't easily find) and completed the rest of the trip with a Marathon XR. Almost 13000km with same front tire and only two back tires - made me a fan of Schwalbe. There were some rough roads there including ~1700km of gravel roads along the route.
Uh, that sounds really interesting. Do you have any notes about it on the web? I really wonder how was the trip in Siberia where some federal motorways are still unpaved.