Seems to work the way we expect, or at least have now learned over time
With all CH OFF then a press ON/OFF turns them all ON, the next press turns them all OFF. If any CH is ON, a press turns them all ON, and another all OFF, so if any CH is ON the next press of ON/OFF turns them all ON.
The GPP-4323 works as 2N3055 describes with the Rigol.
See the point tho, this SPD behavior could easily confuse and lead to a problem, thanks BillyO for pointing this out
Best,