The distinct timbres of the three main registers on contemporary pianofortes would be audible nearby, less so on the dance floor, where the swishing of clothes and muffled swish-slide of light cloth dancing shoes would mingle with the music.
Since writing that sentence, I have been wondering about those shoes. I wrote "light cloth dancing shoes" (that is to say, shoes of a fabric, shape, and weight similar to modern ballet slippers) because those are recognized as the standard from historical sources (dance instruction manuals and iconography). Here is a close-up from the rightmost couple in my logo graphic. This comes from 1808 and so can reasonably be regarded as typical at least into the early 1820s, and the dancers are dressed in a way that corresponds to the social class of Schubert and his friends.
A dance party (house ball) was not like a Clara Schumann recital -- strictly ordered, staid, and quiet. And since one of the few predictable elements would have been the alternation between dancing and eating/drinking, one has to ask whether the participants changed their shoes from one to the other. Given the protocols for dress, it would seem uncouth (or else youthfully rebellious) to wear dancing slippers while eating and talking. If Schubert's friends took the time to change their shoes, that action would would have affected the timing and process of the dancing and therefore also of Schubert's playing: it would necessarily articulate or "formalize" the dancing -- setting a particular dance segment off, as when a modern dance band takes a break. For Schubert, the inclination to group his waltzes by some (any) sort of connecting logic would have increased at least as much as with the "endless cotillions." In fact, perhaps more so, as he would have had more opportunity to organize distinct, small sets in the dance-trio(s) mould.
