I wouldn't recommend to sell all your Bitcoins at this time because the price is still rising and growing more popular everyday.
Unless you really need the money then I would say to sell everything otherwise don't do it.
Why do so many people focus on selling all their coins at once while they can just sell a small portion of their coins? That would make a whole lot more sense as you'll be able to benefit from each market movement. UP - you get to benefit as your other coins gained value. DOWN - you get to benefit in the way that you can buy back more coins for the same amount of fiat. Same basically goes up when it comes to buying -- never buy with all your funds at once.
If you think the price will go down a lot definitely, then it is better to sell all and then buy back later.