I've levelled corruption up to 31 and I'm really enjoying it, not had too many issues. In fact I found elites easier because I can keep Khem alive longer. You just have to put a bit thought into pulls, use cc, stuns and interrupts (especially with large packs) and keep static barrier up on Khem.
One thing I will say is make sure you put 5 points in to the 1st tier of the Lightening tree to get the talents that reduce ability costs and increase your Force pool.