I'm 2 weeks shy of a full year playing this game and I have never, ever
seen a LFM mDPS - I have seen LF marauder often enough and I see LF rDPS multiple times every evening. OP wants to raid? Rolling a DPS assassin will crush his/her spirit. That being said I've been deception since day 1.. LOVE the playstyle (and nope, I don't PvP). Damn difficult to learn the mechanics though, spending as much time on the bench as I do
I kinda feel sorry for you and the server you are on. On The Shadowlands we LFM DPS. Thats it, first come first serve, been in a group with 2 maras, PT, and my Sin, no issues.
When we do full guild runs we try to keep one of each AC, with all the different combos it works out really well as a raid comp. We will still bring a player before class but its not often we are come to that crossroad with most of us having one each of the "4" roles.