The ability to edit edit sliced samples. Using decays, sustains etc. Some samples need to be “clean” when sliced get rid of clicks etc
I have to agree with this; not being able to edit the individual slices is annoying, and the fact that triggering a slice makes the sample editor display a ‘ghost’ sample corresponding to the slice makes it impossible to edit slices by zooming in on the overall sample. Can this behavior be disabled? I don’t remember it on previous versions of Renoise, and it’s been bugging since I’ve switched.
It may be inconvenient, but you can use ‘Destructively render slices’ (Select all the samples + right click) in the meantime.
Go to the sample editor and uncheck “auto-select played” in the top left corner. Now you can play each slice but it will stay on the full sample.
Have you tried using the autofade setting enabled?
Yes that’s awesome isn’t it? especially since it’s an , i love that 
just have to remember it’s there 
Also, when you zoom in a little bit on the full sample, you can still have custom decays in effect e.g. by use of the Fade In/Out keyboard shortcuts or the Sloper tool!