USAF Captain Edward G. Sperry testing the B-47‘s Navigator downward ejection seat. Sperry was one of the volunteers who conducted those tests at the Wright Air Development Center during the early 1950s.
One amazing photo here. Not the seat you wanted in a hurry down low.
Aviation Rapture 
“You’re going the wrong way!”
My friend in high schools dad was a fire fighter in the USAF, first at Edwards during the Chuck Yeager years, then in Alaska during the F104 days. He said those downward seats were the ones he dreaded the most when there was a crash!
I wonder if there were fewer compressed disc problems with downward ejection.
Interesting thought indeed, Gareth. Looks likely.