More good news: just got off the phone with the machine shop, and after examining the oil filter that was in the car during the dyno session, they're pretty confident that the type / concentration of particulates in the oil is normal for this stage of break-in. Seems like I overreacted, but I'm going to chalk that up to an abundance of caution about the $yikes and hundreds of hours under the hood of this car.
edit: Also overnighted an oil sample to Driven's analysis lab this morning, looking forward to seeing what they have to say about it.