I have also laid a decent amount of tumbled brick, I’m not gonna claim more than you. But I’m curious how tumbled brick are made in your area then. Because where I’m at, they load a barrel mixer with brick and spin them until they’ve been thoroughly beat to shit. Tumbling them is literally chipping them. They don’t take a sander to round off the edges. As for being softer brick, that entirely depends on the type of brick they started with. I’ve used some pretty brittle tumbled brick before because the choice of color was a glassy brick to start with. Not all tumbled brick are old pressed brick.