This AHAH-when-form-altering-CCK problem is quick common, and as you found, I don't think there's a good writeup on it.
Could you post your experience with some sample code in the Examples issue queue? We can add it into the AHAH example, as it really is important.
BTW: It all seems to work fine without problems in D7.
-Randy
Of course...maybe if I cleared cache.
Perfect ending to the year! Not completely clear at all on the ahah-cck issue, but hey, that it works is just fine!
Thanks all. May we all byte and nibble more bits in the new year.