Sorry for the slow reply (though it looks as though not too many folks are on the edge of their seats about this topic anyhow)... But I have to agree that Landowska's recordings are not ones I would turn to these days for examples of "historic" - her instrument, her temperament (tuned in equal temperament), etc. are just not historic at all. That's not to say I don't respect what she did in the time she did it - I just would not turn to these recordings for "historic" perspectives. But that's harpsichord, anyway, and the original question was about historic pianos - of which there are SO many varieties, evolutions, etc.
I'm afraid I am still searching for that special and magical recording that gets even close to capturing Chopin or Beethoven (in general) in the same way that being in the intimate presence of an instrument appropriate for their music is so amazingly magical and moving (when played well).
As I mentioned in another thread, though, I do have a Chopin recording - done by Trevor Stephenson on an 1840's English cottage piano. I have to admit I don't care for his interpretation a lot of the time, but the instrument itself has a voice like no other piano I've heard - gossamer, intimate, capable of being quite poetic. I am not totally convinced it is a good representative of Chopin's beloved Pleyel, though the instrument is enchanting and worth a listen.
Other recordings I have enjoyed include some by Ronald Brautigam on historic instruments - you can sample some on youtube. Check out the Waldstein with the lovely and resonant bass:
There are also many good recordings that have come from the former "Shrine to Music" in South Dakota - a gem of historic instruments seemingly in the middle of nowhere. There's one I particarly like that is recorded on one of the earliest examples of a pianoforte that DOES seem to capture that instrument well. It's pretty amazing. Not sure these recordings are available to the general public or whether you actually have to visit... (which I'd recommend, too, though note that you will not be able to touch or play any instrument - they are fiercely protected for historic study and documentation.)
Another I hear wonderful things about is one called "Beethoven in the temperaments" which I have yet to acquire. Several other recordings on my wish list which have been recommended to me, but which I cannot speak to, myself (yet):
•Chopin Nocturnes (on an 1836 Pleyel) by Michele Bgoegner (Caliope, CAL 9281.2)
•Chopin: Eveningss Around and 1831 Pleyel, op. 111 OPS 30-286
•Chopin: Mazurkas and Nocturnes – Zvi Meniker (Trondlin, 1828) Raumklang
Wish I could be a better "recommender", but maybe there's a place to start. REALLY what I would recommend to anyone is to make a point to hear these instruments in person wherever/whenever possible. Schubert club in St. Paul. Frederick collection in MA. "Shrine" in South Dakota. Just to name a few reservoirs of such instruments. Also individuals and university programs can be anywhere.
I'd be interested in anyone else's recommendations too!
JH