There's alot at risk here. What if you ate a Fruit that gave you no immunity to swords and bullets, and was actually pretty sucky? Also, you couldn't be in water for the rest of your life.
However, Oda's been far too leniant about "Swimming" with Devil Fruit Powers, so it doesn't seem like a handicap at all.
However, if you get a shit power, like to power to grow a beard in seconds, you're stuck with it the rest of your life.