The problem with differing translations is not necessarily the words that are used, but that these wording differences are used by some to promote doctrine that isn't correct...
(NIV, 1 JOHN 5:7-8) "[7] For there are three that testify: [8] the Spirit, the water and the blood; and the three are in agreement."
(KJV, 1 JOHN 5:7) " For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one."
Some Christian denominations do not believe in the Tri-unity of God...and they use the wording in the NIV translation to support that position.
THAT is where the danger lies. But for those mature Christians who have a solid understanding of Biblical doctrines, the particular translation used shouldn't make a difference.