I do not have one, but I have used it for like a day and with turntables.
Now for the good things: It is one of the best non NI Traktor controllers I have tried and the jogwheel integration was far better than most controllers. Also the F/X section was really nice to use and browsing was a charm.
The unit is really build like a tank and should withstand small tactical nukes at parties and gigs.
As for the turntables: I used the 4Trak as a standalone mixer to master out. I really had trouble to get the output signal I wanted, maybe the “phono” mode was a little off on my unit and the resistance was wrong, but for me it was not so good. Also the EQ seemed to color the analogue signal quite a bit (apart from the EQing).
Now the unit was not mine and was heavily used, so maybe that was due to the high usage or a problem of the unit. So maybe someone with longer term experience can comment.
Hope that helps 🙂