Thanks for the detailed feedback!! I'll definitely make some changes based on it.

Vote slider: I'm considering adding a cancel button for the user to remove their vote, but voting multiple times isn't an issue - at the end of a slider movement, the user's anonymous profile is updated (max 1 vote gets counted per user)

Colors: good call, I'll change the color pool to avoid clashing with the map.

Slider scale: that could help a lot. I'll try to put something there and see if it makes things too crowded/info dense.

Demographics: I've got the code ready to go for per-demographic stats! The site started with stats and one map data layer per demographic but that scales badly with the number of questions. I removed both at the same time, but I can easily re-add stats.