There are three main rules that govern the 3.5 ruleset with respect to primacy in conflict.
- When two rules conflict, core version and / or first published is assumed to be correct.
- …and specific overrides general.
- Updates to core rules must be in errata format.
Ome of the reasons why they had those rules was because WotC developers were not allowed to reference (for the most part) any books other than core when writing rules. Which is silly in my opinion, but there it is.
Another reason is the rule that updates to core must be given in errata form. Which WotC promptly proceeded to ignore whenever they felt like it. rolls eyes
So, when a rule with the same name or similar effect was released, and one was in a core book, core version automatically “wins” and is correct.
If the rule covered a more specific case, then it wins instead.
Any update to existing rules should be tagged as errata.
Thus by the established procedures of 3.5 the core version of that feat is automatically the correct version, UNLESS the CSoD version is tagged as errata, or covers a more specific case than the general case covered by the core feat.
Please note that while what I am saying holds true for 3.5 material, if we would take control of 3.5 through the Dark Sun material, as I have suggested elsewhere, this could be addressed. Obviously, we would need an active Council or Senate member who could update the site for us, or get one of us elevated to a position of trust and authority so we could do it ourselves.
This is not the first time this happened either (I’m looking at you Cosmopolitan feat).