Scania mid lifts do not raise fully when loaded, though obviously you can transfer weight off said mid lift below (if i recall correctly) 20mph loaded so tyre scrub isn’t really an issue should you end up with a non second steer, weights imposed on mid lift and rear come up on the dash whilst weight is transferring…handy feature that because once you’ve used an axle weigher and know what you real axle weights are you can make use of the air transfer reading to give you a fairly decent idea of weights imposed in the future if you should have an awkward load or use various trailers.
You ask about difference in scrub between fixed and steered, i’ve driven both sorts for years and there’s very little difference for me, but i dump the mid lift air at every opportunity presented, that’s extending the life of the mid lift tyres by some 3X the wear rates of others in the fleet, also cuts down on drive axle scrub due to wheelspin, as with so many things its the driver, if allowed some control, that makes the difference.
MAN and Daf mid lifts do raise fully after a few seconds when loaded for maneuvering and slippery starts etc.
You might be surprised just how heavy a new gen Scanny is compared to the old model, similar spec is getting on for 500kg heavier so might be worth getting a potential purchase weighed beforehand.
MAN and Daf are considerably lighter.