@GIMP
Are those like linked smart objects? Layers that point to files? Because that is the single biggest feature that keeps me hogtied to Photoshop.

I sure hope it's possible to scale each linked layer in different ways. That's something that even Photoshop has not figured out how to do yet. I don't always want to use bicubic scaling. For example my pixel art requires nearest-neighbor scaling. My inking layers need to use bilinnear scaling to recreate traditional anti-aliasing.