I think we're all in agreement that on no playtest material.
My concern is that the stuff marked "debut" aren't really. Yes, the final version that's on paper right now is fixed (where ever it is in the printing process); but that not necessarily what is online right now (regardless of what the DDI says). I'm not convinced right now that the monk that is "debut" will be the same as the monk that's going to be printed (regardless of what WotC says, as the debut material is a marketing move, not a Design/Dev move).
As a judge, when you check someone's PC, do you open up 5 books to ensure that everything they wrote is correct? Or do you click on their feat and item links and check their powers via Compendium? Obviously, the second way is much faster.
The problem w/ approach 2 is that debut material hasn't been errata'd before the book comes out. So, since we get material 6+ mo before the book comes out (as we did w/ PHIII), we won't see any errata until then. So, while WotC does generally get to fixing, debut material seems to have a much larger lead in to such fixes.There are two possibilities:
1) WotC gets it right. In that case, no worries.
2) WotC gets it wrong. In that case, it's very possible that nobody will catch the error in a reasonable time frame anyway.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.