Full credit to Steve Canueto at DDJT

"Track previews - This was a big one for me. I like to quickly skip around tracks in the browser window and preview them in my headphone cue to remind myself of the vibe and whether it’s a suitable next track. This is easy to do in Rekordbox DJ, plus you don’t need to load the track onto a deck - you just click around the waveform in the preview player, and it doesn't mark the track as "played". It's a different story on a CDJ: you have to load each track and manually search through it. It's more time consuming, and causes me to "settle" for a tune because I got bored repeatedly loading tracks and running out of time to make my choice."