I'm using Photoshop CS6 and I haven't had any of the problems you describe. "Save for Web" supports 8-bit PNGs. Exporting layers with a sequence of 4 commands isn't a burden. My Mac Mini loads up 100MB+ files all the time with no problem. I enjoy working with each pixel so I can make it pixel-perfect.
Sorry, I meant 8-bit with alpha channels. The four commands are for Fireworks, I have no idea how to do the same in photoshop. PS is miles better for pixel-pushing, but that doesn't make of suitable for a web design workflow.
