IMHO the biggest advantage is the RAM->GPU VRAM pipeline, or at least, that was my experience before - whatever you want to send to the VRAM, it has to be in RA

IMHO the biggest advantage is the RAM->GPU VRAM pipeline, or at least, that was my experience before - whatever you want to send to the VRAM, it has to be in RAM first, and you have to wait until it gets copied, before you can use that RAM again. With unified memory it should not be necessary anymore (you just mark that part as input for GPU). Same should sort-of apply for iGPUs but I'm not 100% sure. And given that the whole MacOS is built around various GPU-accelerated frameworks, it kind-of matters a lot.