On my 8 speed, I did have a 1 instance where when decelerating the trans aggressively downshifted compared to normal. never happened again, so far I'm at about 700 miles with it installed and no other issues.
Added a carven catback last week and am very relieved to have dfm so there is no chopper noise when cylinder deactivation is enabled.
I 2nd enjoying have auto stop disabled all the time.
And I'll also piggy back off of Dave, DFM is really not that bad and the difference between it being on and off in terms of driveability is negligible. I was most excited about getting it turned off for my exhaust just to make the noise more enjoyable. Coming from a 2015 silverado with a diablew tune with AFM disabled, I agree you have to have a good reason to spend the money on it as the improvement is so marginal.