Here's a picture of the water passages on an LA E head & a W2....

There is absolutely no difference. So the theory about Cometics not working on LA E heads is thrown out the window as I thought.

They will seal water just fine if properly installed. I've never had a problem with a set but with so many people claiming there was an issue I figured I'd check the passages out & lay a gasket on & look for any issues, I found none.