I was keeping quite here because I was not sure either way and I was hoping something would convince me sooner or later but, alas, that did not come to pass and with voting starting soon I thought I should state my (uncertain) position.
I will keep this fairly shorthand because there's been lots of prose already and I don't think anything I have to say is news to anyone.
Reasons to vote ban:
MMX with psychic surge suport has a very limited list of switchins and most were niche before USUM.
This is what I see as the main reason: No psychic surge means priority is much more viable so offense can revenge kill things with speed boosts much more easily which enables much more freedom than running unaware and/or prankster haze/dbond or scarf chansey (which doesn't help with Unburden). With -atespeed, Triage and more varied Prankster moves there are many more ways for an offensive team to stop setup sweeps.
Reasons to vote DNB:
I dont think any particular set with psychic surge is banworthy on it's own, most of the arguments for ban hinge on team support and the overal effect banning would have.
Just to single out mmx (although a similar statement applies to mmy): there are quite a few reasonable checks to surge or surge supported mmx. FC yveltal, FC solgaleo, Misty Surge Giratina, Mega Sableye, Cresselia to name a few. All of these checks CAN be worked around or broken, for example with Fleur Cannon, but the same can be said for the checks to the vast majority of offensive threats and non-surge mmx have always had numerous ways to break their checks.
I am leaning towards ban because from my experience in the suspect ladder I feel it is a more varied and healthy meta but I am torn between also thinking the ability in question is not "Broken".