Wow, that's strange... I tested again and zeroing the yy bytes in the regular Wiimote doesn't change anything (it still works fine), however, zeroing the yy bytes in my Wii Remote Plus made the "invalid packet type" errors popping again. Maybe it's something specific with the very first units of Wii Remote Plus (the non-TR ones)?
There's actually a heap of different wiimote models, if you look at the sticker in the battery compartment it will have "RVL(X)-1" (where X can be F, H, M ...) and from looking at the full EEPROM dumps they all have slightly different firmware.
Do the "invalid packet type" errors contain any other information, like what the bad packet type is?
No, it doesn't show anything else in the console, just that line pops out. I looked at the sticker and couldn't find the info you said, but I'm uploading a photo of the sticker (sorry for the bad camera), it may be useful for you, the white is the regular Wiimote and the black is the Wii Remote Plus...
It's normally in the same place as where the "LMB-RVL-WR/F-C0" text is on your wiimote+. I have one which probably matches your regular wiimote (same FCC ID, which also seems to change on each model), it has "RVL(M)-1" written there.