I think in addition to the record and overdub modes, we really need a "replace" mode.
In this mode, after you have already recorded a loop, if you step on record again, you begin to create an entirely new loop that replaces the old one.
This will allow for the looper to be more functional, imo.
For example, play a riff and jam/sing over it. Then hit the replace button, and record the next part of the song and repeat.
At present, without this functionality, you have to stop the loop, then erase the loop (possible by holding down stop for a few seconds), then you have to hit record again.
Really kills the flow while jamming. I have to pause every time while erasing a loop completely.
The replace could just be a selectable option on the play/overdub button.
In fact, I think it would be even more handy than overdub because how many of us would really use a one-loop looper for serious looping?