My thoughts are that it would be a LOT of work for very little gain, and that work would bring with it a lot of additional bugs and issues. Shader Compilation works mostly off of the CPU right now, you could always upgrade that instead if it’s that much of an issue?
Honestly though, compile times for me have always been pretty quick (less than 20-30 seconds when updating/opening a new project with a lot of custom shaders), even with shaders as high as 350 instructions. If you’re working on a shader and it’s compiling while you build it, you can go under the ‘Usage’ drop-down and un-check everything temporarily. When you re-open the material it should compile in the preview window much faster. I do agree that overall iteration times are much longer than they were in UE3, and displaying the preview material during changes rather than the previous material makes comparisons very difficult.