Anandtech stated that if used correctly the eSRAM makes the difference between DDR3 and GDDR5 negligible. The GPU seems to be a bit of a different story though.
With respect to Anand, he's not a developer and won't be dealing with the rigors of actual software development. Real word development will be the test.
If the eSRAM solution were that elegant a solution, I doubt Sony would have rejected it outright. According to Cerny they evaluated that approach and favored the more expensive unified GDDR setup. There's nothing revolutionary about using a cache alleviate bandwidth issues, it's the natural approach.
But there's no getting around the reality that eSRAM solution in the X1 is a compromise. If it yielded the same memory bandwidth result then Sony would likely have followed suit.
There's a technical advantage a very real one. How that translates to game development will not be clear, as so many other factors, technical and otherwise will shape the way games are made for both platforms.