Update: Please see Insane in the Membrane No Longer Requires All Reputations Simultaneously.
Many people wrote in over the past few weeks to report that their progress toward Insane in the Membrane was stymied. When they gained Honored with Bloodsail Buccaneers, it showed as achieved on the achievement tracker, but when they lost the reputation it disappeared again.
Beginning with Patch 5.0.4, gaining Insane in the Membrane now requires that all reputations be held simultaneously. This means that once you gain at least Honored with Bloodsail Buccaneers, you can no longer lose it until you complete the Feat of Strength, or your progress will be lost.
When Insane was first introduced in Patch 3.1.0, it did not require the reputations be held simultaneously; one could gain the reputation and then lose it later, and it would still count. This is no longer possible.
There is an exception, though; if you obtained the achievement progress in your tracker prior to 5.0.4, and don’t subsequently lose them through reputation changes, then you may be able to keep them and not have to redo those reputations. Don’t count on this working for you, though; it covers only the fairly narrow circumstance of having obtained progress credit for Bloodsail (and possibly Booty Bay) before 5.0.4. However, going forward, you may be hit by this, especially if you are starting for the first time.
My Insane in the Membrane guides have all been updated to reflect this change. Further changes may be forthcoming as I revalidate various bits of information that might have also changed, but since the feat is now awarded account-wide I will be much more reliant on my readers to report errors and changes. Please keep the emails coming!