Good OP. The memory configuration is a very differant approach to current gen consoles. It seems nintendo went with a slow RAM for none vital code and super fast ram for vital code. My guess is they dump everything into the DD3 and then stream out the necessary bit's in to the Edram (the low latency between the DD3 and the Edram seems to indicate this). This approach could be why there are long load times on certain things. Is differant from the current gen and devs probably aren't used to it yet. Current engines certainly are designed for it and will require a fair bit of tweaking.
However what must be remembered is mature, current gen engines are running on the machine and are pretty comparible with 360/ps3 performance.