Good work, Don. You did well, especially considering the solar storm & aurora that occurred during the CQWW, and where you were located during these events.
I wasn't on for the CQWW last month myself, as I'm tending to new antenna installations at home, but some friends of mine worked VB2V in Zone 2 and did extraordinarily well, I'm sure in part because of the somewhat rare zone.
I have also noted the pheonomenon you describe, where QRO is not much required on 10m, and much more required on 160m, etc. I always attributed that to: (1) It's easy to build/buy/install and make work gain antennas on 10m; (2) It's easy to get 10m beams up high enough above ground that they really work well -- 2 wavelengths is not difficult, and 3-4 wavelengths achievable for many; (3) It's difficult to build or install antennas that don't have severe "negative gain" on 160; (4) HF noise levels are most severe on 160, and least severe on 10, most of the time. (5) 160 is only useful during dark hours, which right now is about 12 hours a day; 10-15-20 can be useful nearly 24 hours a day. And all the other bands fall in between.
When I operate at my "big gun" station back east (K2XR in NJ, big beams & big towers on a big hill), I have often noted that if I flip the amp "off" on 10 or 15 meters, it hardly matters. Can keep a run going either way. The amp really is important on 160, a bit less on 80, a bit less on 40 and so forth.
73 de Steve WB2WIK/6