That first presentation was pretty insightful.
I'll toss this in. It is also pretty interesting...
http://www.greencarcongress.com/2009/04/developing-ecoboost-20090429.htmlThis article, unless I misread it, indicates the 3.5 EB specifically (and like nearly all GDI engines) only utilizes stratified lean burn at cold operation. All other conditions prompt homogeneous charges.
Though, it is described as a transient phenomenon in the first presentation in the OP. There is likely quite a bit of soot formation under the onset of high load situations.
Of course, I'm still trying to figure out how the 3.5EB operates in a closed loop control feedback at all times, save for cold start. You'd think as a result there'd be fewer soot deposits.