"Old YC5" no longer available in v.5?

It's the same case for all v4 instruments. That's why Pianoteq 5 doesn't overwrite Pianoteq 4. Keep both installed side by side for compatibility with your existing DAW projects, and older iteratinos of Pianoteq models.

I miss the Clair de La lune mp3 demo.

What about render the midi perfomance with the Kremsegg Bechstein or U4 and K2 and add to the website?

Beto,

while the midi for that particular demo doesn't seem to be available (I assume you mean the Hugh Sung one from the Pianoteq 3 examples), many of the other examples are based on the E-Piano-Competition, and sets of midi files from several years of that can in fact be downloaded, starting with the most recent year available here: <http://www.piano-e-competition.com/midi_2011.asp>.

This can (in my opinion) be a great way to try the sound of Pianoteq's various instruments, even with the trial version, on a much broader scope than just any single person's repertory. Only recently discovered these myself, and find them a convenient resource for certain experiments with the instrument settings, if only as a first step, as several aspects can only be judged when actually at the keyboard, taking into account the adjustments (however minute and subconscious some of those may be) we make in our playing based on the response of the actual or virtual instrument.

Maybe some other readers will find this useful.

Best,
Dan

PS: Be sure to use the XPMIDI files and set the MIDI dialect in Pianoteq's options to Disklavier XP.