Quote Originally Posted by Lithium
An flush draw+ openend straight draw is only statistically ahead of a single pair after the flop. Change the villan's hand to either two pair or a set, and you are behind. I wouldn't recommend always shoving in this situation. In any event, you are still on a draw and need to improve to win the pot. You may be able to bluff a fair share of these, but as you noticed in a lower buyin NLHE, there is very little fold equity against some players.
Note in my assessment I said "unless villain's raising range is two pair+". Against a player who can laydown bottom two pair on a drawy board, shoving is the right play.

Also note that I said OESD + Flush Draw + overs. Even if you get it against 2pair or a set, all your straight outs are good, and at least 7 of your flush outs are good, which means you have 15 live guaranteed, not to mention the .25-.5 an out you get for possibly backdooring two pair yourself.. Usually there will always be enough dead money behind to shove, especially if the pot is multiway on the flop with a caller behind the flop opener.