I had the opportunity to test Warlock as mdps over the last two days and wanted to give my feedback, especially regarding a MAJOR (at least in my opinion) problem in the current balancing progress.
We did a rofl run with two dps yesterday, Warlock/Warrior & Mage/Warrior and overall we had a smooth run, so both classes are actually quite good and able to handle all content. After these first hand experiences I can confirm what was already said by Madoxx and Burningflame, Warlock is pretty good in longer fights and seems to be in overall dps better than Mage (although seems slightly behind on bosses, at least compared to M/W - pre patch).
Today I did rofl with several pdps involved (S/W, S/R & R/Wl), again as Warlock/Warrior. I stood no chance because 1. Everything died way to fast (casts vs instants) and 2. Because only pdps siege titles and Lute were used.
So PLEASE, as already suggested, remove shared cd from Lute & Guitar and merge Regal Cry and Storm Assault into ONE skill. Because right now, you can't compare mdps to pdps because there is no equal testing environment atm. This, in my humble opinion, is currently the major problem in the whole balancing process and I can't see balancing coming to an succesful end without solving it.
Regarding warlock in general: Loosing your Psi after combat ends (especially with the latest changes to it), is very, very unpleasant. Please remove PSI deterioration out of combat. If this proves to be too much, the dark damage passive always can be cropped afterwards. Right now, the core mechanic of Warlock just doesn't work smoothly.