Strictly speaking, the errata shouldn't be ignored because they are changes to the rules set.
Certainly the FAQ and cust serv can be ignored without detriment if you are willing to make decisions as a DM based on the RAW only (which is theoretically possible).
While the current regime of rules design and clarification is better than ever, I still don't have any more faith in the RAW than I did 20+ years ago.
In past editions of the game, I've seen classes proficient with nonextistent weapons, and multiclass combos change from one printing to the next.
Currently, I can look in my PHB and find explicit references to "fists" as Natural Weapons that were
added to the texts of certain spells in the revision from 3.0 to 3.5, yet WotC CustServ insists that this was unintended, and that treating fists as Natural weapons is limited to certain base and prestige classes.
There is internal conflict in the RAW here, and clearly at least some of the 3.5 (re)designers thought that fists were indeed Natural Weapons (a position with which I agree)- which ones and how many is a mystery. How are we to resolve this RAW? Only by ignoring certain sections and using others- hardly elegant- or following CustServ's suggestion...but that suggestion is apparently null & void since its trumped by the RAW...
IOW, its a straight-up DM's call.