I have had 2 floods on my unit (No 44) sinceI got it 11 months ago, 1 without membraine and 1 with membraine. I am not an experienced CCR or technical diver and so I have put this down to my own learning curve. I have since done quite a few dives, my longest is 180mins and have not had problems for a while. I think my problems were down to poor neg's due to the OP having crap on the valve.
In answer to the cocktail, I did get a cocktail on both occasions but it felt much milder with the membraine in.
In speaking to Jason he told me to drink Coca-Cola after a mouth of cocktail as it nutralises the acid and I have to say it works a treat
Hope this helps
L