You shouldn't look at WiiU's eDRAM as 360's eDRAM increased. The latter was merely a framebuffer (though Xenos could output directly to main RAM as well, but you wouldn't use that for normal fb purposes). On the WiiU the eDRAM will likely also host local render targets than never have to leave their spot during their lifetime (ie. never have to be resolved to main RAM). That means such render targets could be use BW and latency beyond the capabilities of consoles we have seen. For example, a 2k * 2k depth-buffer render target (which, depending on the shadow technique employed, could result in very nice shadows at 720p), would occupy a tad over 15MB - depending on the rendering particularities of the game (size of main render targets, other uses for eDRAM, etc), that could result in quality of shadows never seen on consoles before. But this is an ultra-trivial example - way more interesting are the things that the CPU and GPU can do between themselves. Think CPU reading back render targets at impossible speeds, CPU passing down data to the GPU (issuing/modifying draw calls) ultra fast, etc. All those things require modifications to existing pipelines, though.