51.8% makes it seem like an exact number, which it is not. It all depends on the rules of the game.
The way you phrase it, you make it sound like you have some kind of advantage--51.8% chance of winning or pushing. Contrary to popular belief among ploppies, a push is not a win. The right way to look at it is that you have a greater chance of losing than winning. In fact, by your calculations, you have a ~6% greater chance of losing. True, perfect BS, splits, double downs and blackjacks will reduce the dollar risk to ~0.5% depending on the game, but it is still a losing proposition. Except for cover or comps or taking advantage of some other known fact (holecarding, ace steering, etc.), betting more on the first hand is not a smart move.