On the overview page he states this.

I created the MIDI file that generates these MP3s specifically to expose some of the common shortcomings found in the current crop of digital piano emulations.
Manufacturers' demos typically showcase the instrument with a dazzlingly piece of perfectly executed (read: quantized) music that magnifies the strengths
while hiding the flaws. The MIDI file contains two short segments. It was recorded into Digital Performer and played on a Roland XV-88 weighted action
keyboard. The segments are similar in that they make extensive use of the sustain pedal and contain a fair amount dynamic expressiveness. Most digital
pianos can sound anywhere from good to great hidden in a mix. It's when they're played in a solo environment that issues arise. I suggest you listen
to the recording of the acoustic instrument first in order to get an idea of what the music sounds on a real piano.

All of the examples were recorded in stereo and were triggered by the same MIDI file. The many of the orignal pianos were each recorded using the Emu PARIS
DAW system. All newer posts were done using Protools TDM HD. Here they were normalized (when required) and a touch of reverb added equally to all. (Note:
if you're hearing more "reverb" in the GigaSampler pianos this is a result of the pedal down samples being engaged. Also, some of the samples capture
more of the instrument case and string resonance, then do others). Finally the WAV files were converted to 128Kbps/192Kbps MP3 files.

So if there are indeed other players, he should state this. He says all mp3's were done using his supplied .mid file. I haven't had the inclination to listen to each and every mp3 up there, so I can't say for absolute certain.

Anyway, my best piano right now is the PMI Old Lady, and some of their new hybrid pianos are very nice as well. And for 50 bucks a crack for a piano that reaches up to 2 gigs in size, I would definitely recommend you at least give them a listen.
I agree the acustix pianos are the best I've heard for their small size, but they only run in Halion format to my knowledge. I use gigastudio, so they are not an option for me at the moment.