I was dropping off my tanks to get re-filled after a dive this weekend when some guy started asking me a bunch of questions about the gases I was using. Initially I though he was just being curious. I told him I was using 50% for accelerated deco starting at 60 feet (which is well below ppO2 1.6). He then started telling me how he was a Navy master diver for 30 years and that using 50% below 50 feet was foolish because it raises the risk of Oxtox with little benefit in offgassing. He was bit of an aggressive jerk so my initial reaction was to ignore him since everything I've been taught and read (TDI, GUE, PADI) generally supports O2 mixes up to pp1.6 for nonactive, deco portion of dives (again, I was well below this on my profile anyway). I normally don't put a lot of stock in know-it-alls who spout out unsolicited information that goes against the recommendations of well established training organizations. However, on the other hand I don't want to be pig-headed and potentially ignore good advice. Can anyone comment on the validity of his assertion that the increased risk of using 50% below 50 feet isn't justified by the benefit of increased offgassing?