Sal, 1/4" seems common, smaller will induce a more severe deformation as you noted, which of course also depends on how hard you push on it. Most descriptions I have read indicate that you do so until the edge just begins to deform, if you really leaned at max strength and put a few hundred pounds on the edge I am pretty sure you could probably put a perm. bend or chip in any steel.
I have never actually done the brass rod test so I have no idea what it means in terms of durability during use. The idea seems sensible however and I do plan to eventually get around to it as it is a well used standard. No sign of the Guntings yet, which doesn't surprise me as mail here is by pony express.
Sergiusz, I think what is critical is not what is done with the blades but the conclusions that are drawn from it.
-Cliff