I think real pianos sound the best. Everything else sounds like 0's and 1's.

 

I used Pianoteq 6 in a song that I just wrote but won't go there again. It felt rather flat to play as well as the seeming one dimensionality didn't really float my boat

For those who have used both, does Pianoteq 9 raise the level in terms of feel and sound quality

 

Well to my knowledge there is no humanly perceivable mech delay (maybe less than a handful of ms) when the key reaches the bottom (key dip distance) and the hammer strikes the string (blow distance - about 45mm).
The key dip is typically 10mm but I played pianos with more than that, with increasing playing discomfort.

Regarding digital domain, I personally don't get any perceivable delay/lag at all, in sample libraries or Pianteq or any other vst using ASIOat 512kb buffer, and in an 12y old machine.
In past I used Voicemeeter and I could clearly hear a delay after the key push - I wrote about this many years ago, but now with Asio Link Pro router it's ok.

BTW, we're speaking of renowned vsts/libraries, I seriously doubt comments of the kind "this is total crap", without audio comparison/examples/detailed explanations/presets/etc.

 

Ample Sound's guitar manual screenshot

It is indeed very short. I deleted Pianoteq v9 manual so this is from the Kawai MP11 keyboard synth

 

There is no sample piano that sounds like the real one.
Pianoteq is fast and has a more or less convincing sound.
For me as a pianist, Synthogy is the best but it's just my opinion.

 

This is literally one of my mantras, in life in general but especially on internet

 

The reason to use other piano libs would be that you find them more suitable for whatever you are using them for. Maybe tone?