When you need to sync the S2400 to a non MIDI instrument (like turntables), tap tempo is a good tool to find the BPM of a track, but you may need to push forward or backward the tempo to perfect match, like with a turntable.
It could be done with keeping tempo pressed, then >>> or <<<
Or you could adjust the speed on your turntable for the easy fix - alternatively you can start / stop the track on the s2400 while adjusting the speed or buy the Octatrack that already have this feature
Yes i can buy an Octatrack and sell my S2400, but no 
Ajusting the turntable first is not an option because people will hear the pitch change, and you don’t want to disturb listeners.
I believe tap tempo is a great feature but does the S2400 average a number of taps before deciding what is the current tempo ?
Yes! There was a setting for the number of taps to average somewhere.
+1 for nudge. GTFO octatrack.
After tapping the tempo, you can just turn the encoder to adjust the tempo.
What am I missing here?
I was thinking exactly the same thing.
From a DJ point of view, you need two things to mix 2 records:
So, it would make sense to me if the OP meant that TEMPO >>> <<< would be used to make micro skips to the clock (forward or back) possible. But that’s not what I read in his request.
nudge is about adjusting phase without changing the tempo itself. once you have the tempo itself more or less matched, you still may need to make some minor phase adjustments. Its very difficult to do this by changing the tempo and then changing it back it short spurts, its a moving target.
It is difficult at first but becomes natural with enough practice. Similar to the technique DJs use to “slingshot” the pitch fader so that you don’t have to touch the record platter while in the mix.
Shift + arrow keys for fine adjustment is key.
I think I get it. Your start times are off. So, you want to temporarily slow down or speed up the tempo to allow it to get the S2400 pattern in sync with a record. Yes?
By tempo nudge do you mean pitch bend on the master output?
Or real-time time stretch on the master out if you don’t want to hear the “pitch” effect?
It might be too intensive for the CPU.
Exactly. Momentarily increase/decrease the tempo by IDK maybe 5-10%. The longer you hold it the further you are able to bring the phase back in alignment with the turntable. When yo let go it snaps back to the set tempo. Wouldn’t need to do any time-stretching or pitch shifting.
It sounds difficult to implement that kind of function without any real-time effect on the audio. Imagine you have a drum break sample triggered each 2 bars or 4 bars. Even if you do micro adjustement of the tempo, you’d still need to wait until that element is retriggered to feel a change.
Sorry If I don’t get it. 
its not gonna work with live loops and long break samples which have to be played at their natural tempos, but if you have sequences of one shot drum sounds and/or midi notes it will work great for mixing with records.
Tr8s got nudget
I think my s2400 deserve all the features of the tr8 s and more by the DSP card coming
Honestly you’re way better off learning how to ride the pitch on the turntable (so without touching the platter). Learn by mixing disco records with live drums. Once you learn how it will greatly improve your mixing.
Besides I can’t see this feature working properly on the s2400 especially when running external gear with midi clock for example.
Well, if it’s already working with Elektron gear, it can work with anything else, all MIDI related stuff can catch up after some beats, not a bid deal.
Yes
