I do not have an iLok device and so have not been able to download and run the demo versions of Pitch n'Time.
I use ProTools and have been successful in using the built-in time compression/expansion plug-ins to lengthen or shorten, up to 10% or so, complex, classical music performances. However, I now need to lengthen reverb tails by a factor of two to five. By "reverb tail", I am referring to the reverberation present in a performance hall just after the musicians stop playing. In my case, the musicians start playing again too soon, and so I need to lengthen the reverb tail between the moment when they pause, and when they re-start a second or so later.
In each case, the reverb tail originates from a long, sustained note sung by a single, deep-voiced, male singer.
Will Pitch n'Time produce good results? I am a very picky listener, and so any discernible artifacts at all would be unacceptable to me. The results have to be good enough such that no one would be able to tell that the reverb tail had been artificially extended, except perhaps if the someone was told to listen to the reverb tail in particular. But even then, such a listener might only *suspect* that the tail had been "generated", but wouldn't be certain.
My bad, I see you said you can't use the demo, but I it still really is the only way to get the answer you're looking for, Pitch 'n Time gives greatly varying results depending on the material processed.
Perhaps a store would be willing to give you a demo first hand? check out the dealer locator here: serato.com