Manually looping is time consuming and thus unproductive. Most controllers don't use it any more because of this reason.
The implementation of this feature in the Numark N4 is a mapping problem and shouldn't be too complicated. The current 'Loop Out' button goes to 'start autoloop', the one left of it (now Loop In) to 'smaller loop', the one right (now reloop) to 'longer loop' and the last one most to the right to Reloop. This feature is almost implemented now underneath the 'shift' button except for the 'start auto-loop'. The old feature could be saved for those used to it, by getting this feature underneath shift.
I would love this feature because it would make me able to loop in a more up-tempo performance.
To all other N4 users, I know this could make a small change to your routine, but it could make a huge improvement on your productivity. Are you with me?