I agree with Sthlrd. Sidious Sith Master is a really cool piece, but right now he just doesn't have enough good low-cost pieces to work with. Perhaps something will change with the V-set, but who knows? The thing that really makes him useful (moreso in the future than now) is that he can Pawn a non-unique piece which moves into your desired swap position, and then he swaps that piece out for your beatstick...that's 1 activation, and then the other activation is your beatstick's attack. That's just 2 activations for the move-swap-attack combo, which is quite a significant advantage, considering that every other swapper in the game (Thrawn, Panaka, K3P0) requires 3 activations to make it work. Moving, swapping and hitting, all in just 2 activations, is very, very powerful. It's just a matter of time (I hope) before this Sidious is a highly competitive piece.
But until then, Malak DLotS really is the best option that the Sith have.
I also agree with the above comments, that your main 3 attackers will have trouble hitting...+9/+10/+11 is usually just not going to be effective unless you're battling vs a swarm squad. But if you still want to run those pieces, then I can understand, since they're all fun to use.
For reinforcements, you might consider using a KelDor BH in place of the Chag Merc Comm. You can Pawn the Keldor to run it up, then swap it for Maul/Jarael. Now the Keldor is at 30hp, which means that if it's adjacent to an enemy piece or two when Sidious Zaps next round, those enemies will take 70dmg from the 40dmg SD and the 30dmg zap. Not bad at all for 13 pts!