Palpatine did keep some dark side force users around, mostly in one cultish group, including his head of intelligence, 2 Grand Admirals, at least 10 "Hands" (including Mara Jade, Lukes future wife), most, if not all of the the Redguards were force sensitive, both Palpatine and Vader had other side "apprentices" (IIRC, in Force Unleashed, you are, in fact, Vaders "secret Aprentice"). Also, there were many other sith cults, Jedi on the run losing it, and Sith Lords Ghosts possesing the body of powerful force users they find (untrained, similair to daemonic possesion of untrained psykers), and trying to rebppt the sith empire from when they were alive.
also, when Bane set out the Rule Of Two (opperating creedo, sith code is the start of my sig.) he did mention that other, useful force users could be corrupted, and fed the table scraps of the dark side. The most powerful of these were on par with Jedi Knights, the weakest were laughable.
Also, Blackhole (the force sensitive head of security I mentioned) was a master at Sith Alchemy (ancient sith technique used to make monsters (Terenterek, mech-zombies, monsters, mutants of great power), these were commonly force sensitive to some degree.
I have a feeling that a war against the Imperium could lead Palpatine to find a lot more "scraps" of the dark sides power, so sith(ish) squad leaders is a possibility.
still, these squad leaders would prob. only ammount to one force-trick ponies (with a lightsaber) who are faster, and stronger than an average human, but still only barely approaching kinda close to SPace Marines S and T. (Think Tsons aspiring sorcerer but more variety, and weaker in physical traits (barring speed)
also, if ne1 could feed me the general (fluff) organization of the IG, numbers and HW/tank distribution from squad to biggest unit they have (barring the whole army) I found such an article on wookepedia for the Empire, but since its a mess, and I dont want to make this post even longer, I will do the comparison work off the thread, and report the results.