I have been playing against mostly marines of various stripes, and have had some luck. Its been my expereince so far that DE need a little extra luck. But that luck is something you can make for yourself. First make sure that there is a good amount of terrain, not just the 4or 5 odd pieces. Second in my list i make of the baron and a swarm of hellions. not much in the way of inf can survive the hail of shots followed up by a close asslt. A haemonculus is a must i used two, giving a pain token to the hellions first turn. 2 units of reavers at least 5 in each unit. and dont bother with shooting upgrades just thoses that make their overrun attacks better. I have killed many a squad with not return damage. (of course after a few times your opponent will target them right away) raiders with trueborn and splinter racks for you firebase. I have used harliquins and they work great but expensive. I dont like ravagers as they get missled to death first turn, no matter how i try to hide it. The rest of the army is wyches and warriors on foot. my new list i am putting together is going to include a ftr an bomber, plus an allied detachment of chaos marines. for the fluff, fabius+ 5 chaos marines+ forgefiend. something thats durable and can pump out the shots. Good luck and take lots of prisoners