I've had L405 for a couple days now and I can confirm that it has not resolved my OTA pixelation problem. I still get brief bursts of pixelation and audio stutters on one channel (ABC). OTA was never a problem before L401.
I think its safe to say the 622 has an uresolved OTA issue, regardless of multipath. In my situation, I have a 100SS on NBC that the 622 has issues with while the HR20 and my TV have none.
Nobody is saying the 622 doesn't have OTA issues, but there are some things you can try like adjusting your antenna that may help alleviate some of it. Even the slightest redirection of you antenna may help.