Those ribs are far more shallow than they look. As John said, the panel easily lifts off for washing as, of course, do the knobs. As far as the splatter zone, it wasn't that much closer than comparable builtin cooktops of the day. When we found mine, it had been used for a lot of years, but while there was grease all over, there was no burnt on grease so the heat did not seem to travel all that far from the surface units. The quality of construction between this cooktop and the standard GE cooktop we had was interesting. The GE had a porcelain under pan, although it was shallower than the one under the WH. In the WH, it was painted. Mine had rust down there so I had to sand, primer and paint the box with Rustoleum. Had I known about two part epoxy at the time, I probably would have used that, but since it is a museum piece, it will probably be durable enough and probably better painted than it was originally.
I still wonder why someone thinks that this is worth $300. It's not even pink or turquoise for the retro look.