About adjusting the starting point of a sample non destructively through the use of a slice marker and still be able to adjust the pitch across the keyboard;
Load up a sample in the sample editor.
Add a slice somewhere.
Go to the Phrases tab and press create phrase.
Now toggle on the sample icon in the bottom left of the phrase editor;
And make sure you select the sliced sample underneath it;
Now if you go back to the sample editor you can see that triggering across the keyboard will change pitch and moving around the slice marker will start from another position.