The signal from KOIN is still really bad, and my email to their engineering staff resulted in nothing but the sound of crickets.
I also had an HDHR3 that just couldn't deal with what this station is pumping out, but was hearing good things about the new tuner chip in their Generation 4 devices. I'm happy to report that the new HDHR4 is able to deal with the KOIN signal, and is showing a steady 100%/85%/100%. The previous HDHR3 unit showed a consistent 100% for Signal Strength, but the Signal Quality bounced around < 50% > and the Symbol Quality constantly dropped to 0.
Since the engineering staff at KOIN appears to think their current signal is just fine, those with older HDHomeRun tuners may want to consider upgrading to a newer unit.