Hi Rachael,

Yes, it makes sense that it is 'on' all the time for the reason you state (new RT's do not have the +/- files) and also that there is an option right below the high quality tempo/pitch stretching option asking if you want to use +/- files, and by default both of these options are off. Those two options would be mutually exclusive if the 'enable high quality tempo/pitch sretching option actually turned off the new engine.

I'm sure you are correct, it is an additional tweak. I found the following in the documentation after my initial post talking about that option:
High quality tempo/pitch stretching improves the quality of tempo and pitch stretching by a small amount. You should only set this if you have a fast computer, and are not hearing stuttering sounds during playback.



I have enabled it here, so far no problems with playback (2.3 GHZ CPU)