These are chat archives for BSData/wh40k
followed by: "They still gain all the army wide-bonuses for things like Chapter Tactics and can use Space Marines Stratagems and the like, so such venerable heroes still fit right in with the rest of your army."
then 2 paragraphs later: "Yes, many units’ rules in their codexes will alter from those in the indexes. Sometimes this is to better represent the miniatures and the background, sometimes to balance the game, and sometimes to better fit with the army’s new special rules in the codex itself. In all cases, these will then supersede the rules for that datasheet in the index book."