I usually don't like posting on these, and I'm not sure if this idea is even good, but maybe reduce demos health instead of his damage so that he can do what he does, but has to actually think more about what he is doing that usual. Maybe put him on either 125 or 150, and that way he can get 1 shot headshot aswell(Of course make sticky self damage less so he can still rollout). And of course pubstomping would be harder aswell.

So I play Demo-man for a 6's team, but I'm always in the middle of my teams logs or lower for damage. I'm always at the top or near the top when it comes for kills though, and I don't seem to die a lot. Does anyone have any tips for how I could maybe do some more damage?