If you can't manage a combined > 50% winning pct vs RMX, KFC, WMX, LSD, God Comp, Beast, and MLX then you can't push it to safe glad.
I personally want to know how it performs vs each of those comps individually
RMX = Finding them on stealth is GG you win. Especially if the rogue and mage plays with a hpala, demo locks pretty much counters any form of direct healing. You'll just have to train the mage. Against rdruid teams it will be a bit tricky, that's when you have to switch on someone without HoTs.
KFC = The demo lock is very tanky against hunters and the lock would give you a big favour if he knows common sense...Such as LoSing the hunter or don't LoS your healer etc.
WMX = Isn't a problem at all, you can go for any targets except for the healer. Infact it's easier than meeting RMX since you can peel off the warrior easier than the rogue since you got demonic gateway and deathgrip.
LSD = a matter of going for someone who doesn't have HoTs and switch on the rdruid everytime you got AMS, Asphyxiate and Deathgrip.
God Comp = Train whoever got no hots, the games takes time but it won't make you lose unless the rshaman messes up with the positioning or yourself.
Beastcleave = Matter of training whoever got no defensive cds, you can train the hunter all day if you want, you can switch for the healer or get the shaman in a bad spot for a hard switch.
MLX = Train the mage and the lock all day, depending on who got no HoTs or defensive cds.
I'd rate the comp vs each of those comps individually.
RMX = 6/10 can be difficult if rshaman gets swapped on, aka caught in a bad spot.
KFC = 9/10 You lose if your lock messes up pretty badly. (Like running away from your portal radius or no gateway closeby or overextending)
WMX = 8/10, the swaps on the rshaman if your healer messes up, he is dead.
LSD = 9/10, the only problem is the dk issues, our survivability...Like AMS for example.
God Comp = 7/10, Dk survivability issues vs silences. You'll pretty much have to stand next to a gateway.
Beast = Same as KFC
MLX = 7/10, Dk survivability issues. Same as God comp. You won't have big chances on having the advantage to switch on their healers.
Personally I'd say try the comp. If you know a lock who got common sense and a rshaman who won't panic as soon as he gets switched on. You'll be completely fine.
What I've noticed is that you can go through any type of defensives except for evasion, cloak and die by the sword with the damage that the demo lock has. The survivability with the lock is nowhere to be an issue. You won't struggle at all. It's just the dk survivability and the rshaman swaps that can be difficult.
against RMD, we've struggled a bit with the damage part when going for someone with full HoTs. Because the amount of peelings the rogue does is insane against a dk. So the best thing is going for someone who doesn't have HoTs pretty much.