Agreed with what Ed said , May be Nebraska is on the dry side all along the year.
Humans also are sufferning from too low moisture level during winter, babies, but not only.
The natural evaporation obtained by "cold" systems (the water is on a wheeel that turn in an air flow) is a simple and not too costly system, that can even be used without HR regulation in my opinion.
More evaporation if the air is warm, less if it is cold, it sort of stabilize by itself I believe.
Also the air is "washed" from dust while passing thru the humidifier.
example : http://www.youtube.com/watch?v=BOvsXL0pk8Y
SOme customers have such models, and are very happy with.
Othere mauy have an higrostat , but unless you buy a professional huùmidifier , the electronics on those sort of things is too low quality to last really long. SO in the end the most basic is the better
(professional humidifiers use the same system most often)
A little moisture for the dry season can just gain you a few decades of fuller tone and avoid any cracks, but sure not all indoors ask for that and modern pianos are more adapted to dryness than older ones)
Despite that even the concert grands are sounding more metallic during winter, and offer less dynamic range.
The Estonian grands are visibly well build, I am not big fan of their treble I find too brutal, not singing enough (for my taste). it may be partially due to the hammers used, but also to , the soundboard and scale, indeed.
If you like that go for it, but remember that the tone get more brillance in time, after a little maturation the tone harden, a piano that tend to provide more partials than fundamental with be clearer soon
WHat would be the final element to ascertain the quality of any piano to me is the thickness and lenght of the tone in the treble
The treble must not be explosive but thick and transparent
You may want to test that quality on different pianos, new or old, by listening to the way the tone expands, diseappear, or stay the same during sustain. the more you hear the "alimentation" of the tone, the more lively your instrument is
you may hear as if there is a small engine that "push" the tone a little after the initial attack . A too straight and direct extinction curve provide a less manageable (singing) tone.
In case of doubt play silently a note and pluck a string, listen to the thickening, is it long or does the tone escape soon ?
Any top technician can take care of a good piano instrument.
For what I have seen the prep is initially well done on Estonias, may be a little correction for hammer spacing , the usual key bedding check after a piano move, some fine voicing, and enough tunings to settle the piano in 2 3 years.
So yes try to get in contact with a good technician before buying the piano, I am sure he will appreciate that, also.
First look for concert technicians (in my own experience teatchers rarely care seriously about their pianos, and have some win win excahnges with their tech so they pay less (or nothing) and have less work done generally as a final result.
NOt very politically correct to state such things but that is some reality in the part of the world I live , of cours there are appreciated exceptions, when you are with real top pianists, this happen more with "ordinary" piano teachers, and even there some of them are attentive to their instrument.
But I have seen enough piano teachers considering their piano as a plumber his electric drill... The fault to the technicians also, that make them ring "Yamaha" or "Steinway" as being enough to consider the piano is in its best condition...