That Dimir deck could *really* use Dead Weight - would probably sub out Mephitic Vapors, and one copy of Ill-Gotten Inheritance. Maybe even two copies of the enchantment for a 25th land, too.
EDIT: Scratch that, the shell's probably not good enough. Yes, you can control stuff, but there're too many things that just beat you - e.g. Martyr of Dusk, Blade Juggler - since they generate inherent card advantage and the sweepers are awful.
EDIT #2: Yup, definitely not good enough. Creatureless control doesn't work without good sweepers. Recommend some other idea instead. Two examples could be UR Spells with Jaya's Greeting, Spellgorger Weird and Aven Eternals, or UB control with Watcher in the Mist, Omenspeaker, Salvager of Secrets etc. Omenspeaker for example is very much capable of holding the ground against red aggro, and will always put you up the scry 2.
Ill-Gotten Inheritance is surprisingly powerful in my experience - there's no way to remove it after it's hit the battlefield, and it's a steady clock that keeps you alive. Also works great to enable spectacle for Blade Juggler.
The extra 2 life and the instant speed of Moment of Craving make up for the mana saved on Dead Weight in my experience.
I absolutely hate Vapors as well, but you need it against the 'go-wide' decks that mostly run 1/1s and it's card advantage vs. mono-red. I'd love to shave them down to 2, but that doesn't quite work methinks.
Cruelty actually gets around many on-death effects because of the exile clause; and most of the comes-into-play abilities you are supposed to counter.
That said, the deck dos have its weaknesses; the main one that I noted being that it cannot beat a resolved
Jade Guardian, and 3 Blink of an Eye might not be enough against enchantments. In fact, I do believe Jade Guardian (and to a lesser extent
Cold-Water Snapper) to be very problematic creatures.
EDIT: TBH; it's very possible Green is the best control colour in the format if for one card only:
Crushing Canopy. Kills any flier or enchant. If you can stall the board enough otherwise, you cn then probably win with your big creatures.
Biggest problem: Basically all common Gx gold cards suck balls.