Bruce
TVWBB 2-Star Olympian
From my experience they, too, get crudded up and can actually contribute to flare ups and fires if you fail to follow very regular cleaning. I think the deflectors are more about evening out the heat distribution. If you look at the older 300 series grills with the E-W burners the surface area with a burner tube underneath is significantly more than the newer 300 3-burners which have pretty big spaces between each burner. It would seem likely that without the deflectors there would be uneven heat with so much between each burner. That is why I mentioned that the sear station fourth burner at least partially addresses this grill’s weakness.
All of the above is just my theory, but a lot of actual use seems to correspond with it.
I have an E-W and N-S E310 to rehabb this summer, so I guess I will get some more experience with them and how they work. As of right now, I am just going off of what I have heard since I really don't have any first had experience with them. I know the one I acquired was so bad, that I didn't think it had the heat shields in it, so I bought a new set, only to find out they were in there, just buried in gunk.