I think there is a place for all row spacing.

15-20 miles north of me, according to University study's, show its close to paying by going to 22", further north = more of a payback.

35 miles south of me, they can't get 20" to out yeild 30's.

Found an old "The Farmer" magazine from 1968.......4 pages devoted to a guy in wisconsin who was running 20" rows next to 30".........Unconclusive responses........I would think after 40 years of trying this, trying that, there would be a set row spacing for corn by now?

If our soils were more sandish, I'd look harder.  We looked hard ten - fifteen years ago to switch, and I do beleive there was a time where we lost yeild in those years......But now with the genetics were planting, it just isn't the case.......Here, out my back window.

Still looking though, things can and do change.

I'd do 20", or 15" before twins.  All our variety's we plant don't have broomsticks for stalks come october.

Just my opinion, and some stats from Mother U.