This stuff seemed to be the workkbench wood du jour since Chris Schwarz published his book, so I picked up some 2x10s from the BORGs cutoff bin several months ago.
I decided to use a 4' piece as a French cleat on a wall-mounted shop cabinet. I jointed an edge, ripped it in half, then jointed a face on each board (no small task given how much wind they had) and let them sit several days.
This morning I tried to rip the two 4 1/2" boards in half at 45. The second I cut this stuff, it twists like a pretzel. Most of the wood is quartersawn. This ended up being too nerve-wracking on the table saw, so I took it to the bansaw. Due to all the movement, I first had to rejoint, leaving once piece of what had been 6/4 stock barely over 4/4. So I resawed to get them all the same thickness, just over 1". What had been a flat, quartersawn, 4 1/2 x 1 3/8"-thick board came off the bandsaw looking like a stave from an old whiskey keg.
And no, it's not pressure-treated.
Dunno what wood my next bench will be built of, but SYP won't be on the short list.