Since 1.5 is about smaller improvements to existing features maybe the design if the LayeredMtl could be reconsidered to make it a bit more convenient for lookdev of complex materials.
1. Currently, the amount spinner is only active when there's no mask in a Layered Mtl - why not always? It probably makes sense if you want to use it for decals exclusively but it's highly inconvenient for adding layers like scratches, dirt etc. Making it work right in the material's main UI would help a lot as it won't force the user to mess around with additional output nodes for each mask, speeding up the workflow a lot.
Also, it forces you to remove either the material or the map in order to switch a material off temporarily - see point 2 below. It would be way easier if you could set the amount to zero.
2. I know this has been discussed a lot back then before the material was introduced, please add a checkbox to each Material layer to allow the user to quickly switch it on or off. If we want to disable a layer, we have to either remove the material or the map or replace the map with a black color. I know one important point was the it would clutter the UI but if it's still a concern, you could solve it by using a 2 lines layout for each layer, checkbox and material slot on the top, followed by the amount spinner and the mask slot. I think this would even help to make the UI a bit friendlier to the eye.
3. I would love to see an option for an additional bump slot that would be applied to all materials used within the LayeredMtl in a screen blend fashion or, if this is not possible, replace them. This would be super useful since currently you need to add the same bump map to each of the materials if you want to make it look like one surface... useful for scratches or general deformations of more complex material setups.
I would love to use the LayeredMtl more but it's really clunky to work with as it is now, especially the amount spinner becoming inactive when using masks.
