I don’t really have the chance to test pianos out
Aren't some stores open (even if by appointment only)? I would really try to get the feel of the action and the sound too.
To me, if money is a concern then yes I would go with a used piano, and I wouldn't go below 5'8". I tested a 1978 C3 sold by a private owner (didn't end up buying it as he was asking for too much), but lovely sound and great action and it was under 20k. The recommendation I read is to have a technician inspect a used piano before buying, it may cost some $ but save more later.
Larger pianos have richer sound as well as a more thunderous bass.
Lastly, about Yamaha pianos, I understood from what you were saying that I should voice my Yamaha if possible. I know that Yamaha has a very bright sound, so the extra voicing would be a very likely possibility, but is it something mandatory to do with Yamahas or should the voicing be based on personal opinion? I myself prefer a warmer sound, but not a dull one so I am curious.
Voicing is not mandatory but very personal

The sound you will get depends on the environment where your piano will be located. Hardwood floor (will sound brighter) or all carpeted (will sound warmer)? Low ceiling, high ceiling? Avoid being too close to a large window as well (oops, I have all these combined, low ceiling, hardwood floor, and large window). I have wood panelling on top of drywall (old house) - I think it brings more brightness and echo.
Other brands may have a warmer sound, like Baldwin, Steinway (warm sound but $$$), Bechstein...
Anyway, hmm, back to work
