For CMs I started out trying them with Servitude/GoSup but the more I did them I realised that the reason warlocks get brought to CMs is for the Aoe, havoc and shadowburn and imo those are the abilities you want to enhance as much as possible, that's why you want to go with GoSac and Cataclysm (no other choice anyway in last talent tier tbh if you pick GoSac).
GoSup + Demonic Servitude could work too but the pet is very clunky a lot of the time. Currently in certain dungeons the pets have a really bad habit of randomly dying or running off for no reason. The only dungeon I'd consider to pick Demonic Servitude in is Auchindoun if you don't have a druid or another really good way to CC the infernal on the last boss (oh shit i might look like a retard here if banish actually work, didn't try it). Even then it's a lot weaker because you lose out on a big part of your dps on the last boss and the packs leading up there are all rather big pulls which favors Cataclysm.
AD vs MF are close but AD provides a lot more flexibility, IE pop 2 DS right at the start, wait 4 mins and pop 2 again if you so wish. Without AD you are pretty much limited to popping DS every 2 minutes which is not ideal in many dungeons.