I had PLAY and STOP buttons getting sticky once the Digitakt heated up a bit. I returned mine, as this kind of problem will likely worsen over time.
Seems like Elektron rushed to market with these new buttons. Having committed to use the same ones on the MK2s as well hopefully means they'll (have to) fix these quality and QA issues.
With the Digitakt being my first Elektron piece, this left me with a rather guineapiggish feeling, especially in combination with the unfinished firmware. Still ordered a new Digitakt and decided to stick it out, because when it worked, it worked great.