As desribed in another topic ( [Win] Rekordbox xml contained some corrrupted data ), I personally really like to edit beatgrids in Serato, especially when dealing with old music and live music. For such songs, the bpm is irregular accross the whole track. The analogy is to have a “transition phase” in an EDM song, but not just one, but one every single downbeat.
You can do the same in Rekordbox, but it is much more time consuming in Rekordbox as compared to Serato Dj. Please be aware that, even in Serato, it is still time consuming. But the end-result is pretty awarding.
If you would like to learn how to do beatgrid “next level”, you can watch the following video on Youtube (not mine, I just found the explanation pretty clear):
If you are a Pioneer Dj gear user, simply use Rekord Buddy to transfer your beatgrid back into Rekordbox so you can use the beatgrid in your club.