What do people think about demos being visible, and you have to be cunning about where to place them?
Yes and no. If you mean needing to place them behind actual LoS blockers (buildings, walls, large vegetation) - I am all for it. It might become a bit too map dependent, but it would be a step in the right direction, and fit well with true sight.
If you mean needing to place them behind objects so the
player has a hard time seeing them from the default camera angle, then please no - that would add an arcadish element to the game similar to tank crushing, that is neither tactics or strategy. I also really dislike how eg. cloaked and burrowed units are a bit visible in SC2, so I might be biased.