I think the lesson learned is to only buy new tyres. The L'zens actually had less tread on them than the Goodyears but apart from slightly soft handling seemed to grip quite well. The Goodyears must have had some sort of contamination though because it was possible to spin them in the DTi before you'd hit the turbo in 1st gear so that must tell you something 
I would like to try a full set of new, matching winter tyres but i'm afraid funds just do not allow for that at the moment...
I think an important lesson, as I said pages ago, winters aren't a magic cure for snow, black ice, whatever. Neither are 4x4s. Whilst they would/should have better grip at low temperatures, they are not a magic cure...
When I used to do a real job, I was called out to a road, report was telegraph pole had been knocked down. Me and my mate turn up, yup, pole down, with a Rover 214 embedded in it, driver nowhere to be seen. Eventually, he appears, still in shock, muttering "this car is supposed to have ABS, which means its safe" as he sticks his foot in one of the headlamps. My comment to him is the same to people here - having some safety feature (or winter tyres) won't save you from driving like a <insert description>
Not suggesting for one minute that the quoted person was or does drive like a twonk. Far from it, knowing him...