Better extendings, there are hard times when trying to extend a track and all goes wrong with frequencies clashings, sub freq is messed up, kick becomes muffled, the whole ext is muddy and harsh. Another Thing would be so cool for example maybe some eq, compressor, de-esser, multiband comp, more consistency with the kick drum so he can cut trough the mix without loosing his characteristics and not morphing, this is also for other elements. I forget to say that those issues also happens in first generations when creating new tracks.