i haven’t tried either of these but I have never seen a bad word written about the Silenus. It is universally loved by all those who try it. There’s even a “Pay It Forward” thread in the BST that tracks a community Silenus bouncing around the country so people can try it for free for a month. ( Pay it forward silenus - Buy / Sell / Trade - YoYoExpert Forums )
As stated above, the Shortcut is pretty new and not a lot of people have experience with it. Looking at the specs, the only difference I see is the Silenus is about 0.1 inch wider and weighs about a gram more. They look very, very similar to me.
You likely can’t go wrong with either but based on the community love of the Silenus, i recommend that one.
good luck.
Enjoy the throw
kgb