As for the who is currently winning in the match between Mind Rot and Duress...
Definitely Duress for the art. But for my sideboard, I think Mind Rot will be more useful. Against decks that are weak against discard effects, namely Jund, Jacerator, and Control decks. (Is there more?) Mass discard is more useful than targetted discard. Especially with Jund since you can only target a few spells in their arsenal like Blightning, which IS a great target but will miss a lot if they're holding ... anything else. Besides that, they can cascade into Blightning anyway. So what's the point. You want to have MORE cards than they do, not "better" cards. They're all fine cards anyway.
Against Jacerator this is definitely the case. They cannot function if they don't have a certain VOLUME of cards. The more you strip away their hand and the faster you do it, the better. And meanwhile you have to destroy the mechanisms they put in place for drawing cards. (Which is why I'm keeping a 4th Pulse in the sideboard also. It's essential to have against them.) With targetted discard, you can keep them from Flashfreezing your Pulses, I suppose. But I think it's better to try to put them in a spot where they're either a) not getting the lands they need because they discarded the ones they were holding b) not getting the fogs they need because they discarded them, and they only run 8 c) not getting the win cons they need because they had to discard Archive Traps or Jaces. Worst case scenario, they discard the Wraths that are bad against Jund anyway. But barring that, whatever they discard, it puts them in a corner. And more Blightning/Mind Rots early are good. Blightnings that can't be Flashfreezed (Flashfrozen?) are good.
Having "more" Duress effects, not so good. Duress is great for the early turns. Later on, you'd rather just draw into a bunch of Blightning effects in order to try to catch them with their pants down.
You still need Pulses to win that matchup unfortunately. I don't think it's possible to win if you don't draw or Cascade into a single Pulse. And you'd prefer to just draw all four...
Against more traditional Control decks, I kind of lied. I think Duress might be better in those cases. Especially multiple. Knowing exactly what they're holding helps a lot. Quite a lot. Jabbing them in the gut while they're setting up mana or what-have-you, definitely painful for them. I'm thinking of RWU in particular. Against Grixis it is probably a similar story. Mono-White Control? That matchup is a little off the radar. It doesn't play like a regular control deck since they don't have any counter spells. I'm not sure which is better for MWC or MBC or any of those. I don't see them as often.
The thing is RWU is very unpopular right now. No one is winning with it. Jacerator, on the other hand, after making 6-0 at Worlds is the big cheese. And that deck rose in prevalence surprisingly quickly. (Probably all those Time Sieve players just waiting for their big opportunity to use Font of Mythos again.) Mill is popular with the kids. Who knows why. And Archive Trap is pretty exciting.
I'm rather disappointed I haven't been hearing, "I ACTIVATE MY TRAP CARD!" more often on the Magic tables. Even "ITSA TRAP" would make me happy. But no.
