I don’t have a Digitakt, but I have an OT and Rytm so here’s some tips:
-Use one shot recorder trigs to capture the current DT pattern as a sample and use the crossfader to mix between the sample and the live DT audio, all at the press of a button without stopping.
You can fade to the sample, switch the DTs pattern, and then fade to that. Of course with the fader in the middle you have 2 DT patterns mixed… Repeat as necessary…
Sampling a DT pattern and mixing between it and a control all version sounds fun…
With the DT pattern as a sample, you can do audio warping tricks like reverse it…
-Have a pre arranged, sliced up remix of a recorder buffer on a flex track. As soon as you sample a DT pattern the flex remix will be available instantaneously, you can use the crossfader to mix that in as well…
-Use a thru machine for adding fx to DT, you can have the crossfader control the fx, sequence them if you like…
All of the above would be controlled using 3 or more different scenes which you select to decide what you want the fader to do…
-Send midi lfos to DT, and also the arpeggiator…
The above is staple OT stuff. For more experimental stuff I’d be interested in using DT’s conditional midi to trigger OT events… Conditional sampling sounds quite interesting for variation, and I’d want to try conditional launching of plays free tracks. OT can have tracks that don’t start with the play button and you can launch them whenever. You could set some tracks as fills or added textures and have them conditionally launched here and there as one shot tracks… With these two in combo you could get some interesting variations of fills or other elements launched here and there, and with occasionally updated samples as you go…
Having the lfos and arp controlling aspects of the DT as said above, the DT could occasionally conditionally change some of the arp or lfos parameters back on the OT, which in turn creates variation on DT…
Really there’s piles of stuff you could do with these two, the above is just a few examples…
You’ve got a little time before mk2, if I were you I’d get to the Dagobah system asap to find master Yoda and begin your training, I think he just got back from Burning Man… 
