My Sangean tuner reports that *all* Portland HD transmissions are in MP-1 mode. No “extended hybrid” here. Many of these transmit HD-1, HD-2 and we have had HD-3 as well. I am thinking that the “P-1” and the higher “Ps” refer to a digital “channels” that may be split into several streams, if desired.
Keeping the Eugene topic, IIRC it reported only MP-1 mode for Eugene stations as well, before the F1-HD replaced it on the Dx antenna. 🙂