Damn. I thought I was crazy. I'm both relieved that I'm not the only one to have experienced this issue... and somewhat saddened to know that Volvo's darling new engine has issues...
Granted, I've not had the dreaded "clicking" power-killing noise for several months now -- not since after I had the recalled spark plugs replaced and my ECU updated. One day it just... stopped doing it. I wasn't sure why or how... but I was happy it didn't do it anymore. Now I can charge off on-ramps all I want and not worry about the power dying out on me.
Still, I'd like to know what causes it. I use 87 octane fuel with no issues. And the one time I did try 93 octane to see if it would get rid of the clicking, it didn't do anything it seemed. It worries me to think what other issues might lie beneath the surface just waiting to rear their ugly little heads. :\