As far as I can gather from just a few hours of use and perusing the manual searching for keyword ‘Truncate’ the only way to truncate a sample is to use Loop/Slice -> Overwrite Same File option. What I would like to see is a way to either truncate in RAM(dont touch the file but clip the region on the track) or a shortcut to Save To Folder that will save the edit with the current file name + . So say I have file BobJames-Nautilus.wav loaded in a track, and I wanted to chop a region from the track for use in a pattern. Go to Loop/Slice and edit the region I want to use. Either have an option to drop the audio data outside of the loop/slice region and leave it in RAM or automagically save it as BobJames-Nautilus-edit1.wav without having to use the encoder.
Bob James - Nautilus! Now We Talking