I cannot make up my mind about this. Where would you post a recording of your own composition ? It would be easy to post an "improvisation" actually composed or a "composition" actually improvised. What about recordings containing both ? What about, say, a piece by somebody else containing improvised bits ? Who is to say what is composed and what is improvised ? Does it really matter ?
While these issues probably wouldn't seriously bother the posters, the moderator may find it impossible to know where a particular recording should reside. Common sense would have to be applied, with one section being mostly improvisation and the other mostly performances of compositions. Having said that, I think it would be a lot more sensible and workable than the Pianoworld split into "classical" and "non-classical", which is just plain silly.