The "wheather" changes you talk about cause a few things to happen. The soundboard is bowed like the lid on a violin. With airmoisture increasing, the soundboard swells, the 'bow' increases.
The strings are connected to the soundboard via a bridge. The bridge slightly rises, increasing the string tension, causing the pitch to raise, changing the angle at which the end of the strings continue to the hookup pins.
With low moisture (winter), the opposite happens. The bow (actually called the crown) flattens, bridge sinks, angle decreases. In a worst-case scenario, the soundboard looses the crown altogether (becomes flat), and this angle from the bridge to the pins becomes too small, causing the string to rest uneasily on the bridge and can cause problems with the tone-production. A flat soundboard will not sound good either.
The same happened to your K52 of course. But differencies in construction will cause difference in effect.
I would be natural for a piano to sound slightly different winter vs summer, but not unpleasantly so, of course.
Steinway is unique. There are more opinions about them than any other brand, because they have the reputation to be 'the best'. Still today the New York factory is to a great extent the same as in the 1890's. The greater part of each instrument is hand made. The rim, eg, is bent by hand, so every rim is slightly different, then each soundboard is customized for fit etc etc. No two instruments end up sounding the same.
All in all, expect your L to have a 'personality' different from any other. But if you are somewhat unhappy with how it sounds and feels, talk to your technician (assuming that he is independent from the shop) and let him thouroughly examine it. If there is something dodgy about the restoration for example, he should be able to see that.
Ask him about the "damp-chaser system". It's a climate control system fitted onto the piano, which makes sure there's a constant 45% moisture in the soundboard.