It's a shame there are not much dark progressive (even progressive-house died long time ago :s ) left today, for dark progressive just a few artists and albums I can remember ... the rest I call it minimal trance with a dark feeling, but not progressive IMO.
I can recall now old Haldolium, Auricular, Sensum, Ticon (aero),Cujorioius One, and a few tracks by Sensient ... yes I know they are all old stuff, but my love for progressive died long time ago when it became to be more and more influenced by electro and minimal sounds.
Being a little offtopic, I think that minimal and electro are the cancer of electronic music today, every thing that touches loses it's soul and become easy, repetitive, predictive and boring. I mean for someone like me who really was into progressive, albums like old GU, Balance 002 - Kasey Tailor, GU NuBreed 006 - Satoshi Tomiie, GU NuBreed 001 - Anthony Pappa, and of course old Sasha and Digweed magic sets; that's what progressive is all about!!!
There are also good examples of combination with minimal and electro that are pretty good like Balance 005 - James Holden, Balance 007- Chris Fortier or some James Zabiela's stuff, but most of the music today that has that minimal-electro flavour I can not stand.