I think would be very usefull and lightweight instead of using layer nodes, mostly for procedural stuff like darkening/tint areas with cuvature/dirt, or lookdev characters with dedicated maps for make up, sweat, skintones.
I believe RenderMan and 1 or 2 other render engines support checkpointing, where there render will periodically save its render progress so if the frame is interupted or stopped, that another render node may be able ton continue where the frame la...
DreamWorks recently unveiled what they call cryptoDeep - cryptomatte support for Deep EXR that supports transparency. This would be incredibly useful for situations with cards with opacity mattes. I believe they said the source code is in the late...