Use Grid To Arm/Disarm Recording
Obvious advantages to automating the record function but mainly for me this is to free up your hands when using other gear with the external IN. It would also record perfect loop lengths and could be made to enter recording and playback on the grid so you can audition the loop for a few bars in between takes...automatically setting up a retake until you nail the part and disarm recording.
Usage: In KIT mode, hold down desired recording start point on grid + RECORD which populates the row with blinking red buttons through the entire length of the track or to the next playback cue and can then be trimmed by pressing an end point on the row. Press the recording start point button again to toggle recording and playback/disarm recording.
Here are some related requests that would mostly be satisfied with just this one. While this request is different than "Start and End Point of Samples", you could technically achieve the same results by automating the start and end points of a resample of the desired sample you want to trim. This request would also streamline the building of multisample instruments by creating a situation where a kit of recording cues would allow you to automatically record one note after another like pre-slicing.