instances and blending modes
When I instance a material or smart material and have the blending mode on the original set to anything other than it's default I have to change the blending mode of each channel in every textureset I have it instanced to, because the instances have their blending modes set to default again. For instance, If I instance a material whose basecolor I want to be multiplied over what is below, I set the blending mode to multiply. But when I instance this material to any other textureset, It comes in as normal and then I have to go through all texturesets and put it's blending mode to multiply by hand. That is a lot of unnecessary work.
A big +1 on this. The word instance implies the layer will be the same - however as the blending modes aren't instanced the end result often looks very different on other texture sets.