I would vote for the Imperial Torte --for me, there is no contest. While one can make the Sacher Torte fairly easily, the Imperial Torte is tougher.
If the torte is Fedexed, it should be okay..... but the best way is to go to Vienna and enjoy it there!!!
I'ved had the Sacher Torte at Demel and I found their version to be better than the one served at the Sacher Hotel...