First off, I’m very impressed with the new instrument features. Renoise has made the transition from a pretty rudimentary sampler to a very respectable one. However, there are a couple of extra features that I think would upgrade it a truly awesome sampler:
Cross-fading between sample keyzones: rather than an abrupt transition or a full-volume overlap (which makes overlapped range of keys louder than either of the individual ranges), it would be nice to be able to gradually fade from one sample to another, so that as you move up the keyboard you hear progressively more of one sample and less of the other.
Cross-fade loop mode in the sample editor: an additional loop mode which provides a resizable area extending before the start and end loop points, during which the next loop iteration is faded in and the current one faded out. This is an absolute godsend for the complex stereo samples where no amount of loop tweaking and zero-crossing-detection can get rid of the pops and clicks. Currently I can achieve this by creating the crossfade loop in REAPER and then exporting the result as a looping WAV sample, but doing it all inside Renoise would be much easier.