I see no reason to spend the extra money on shallow dives. But for deeper dives you can def extend your bottom time. Last week i did a dive w/ air and i came up w/ 1300 psi b/c my bottom time ran out. If I brought my nitrox tank I could have stayed down longer. I do get headaches after diving and when using nitrox I don`t. Also when I was in Bonaire do repetitive dives like 5 a day. the first 2 days i used air and was exhausted, after that i switched to 32% nitrox and felt energized.