I admit that I personally would not want to split my tongue... but then, I'm not really the adventurous type. But that being said, my opinions on not getting it done only really apply to myself. You've been clearly thinking about this for a long time now, and I find it somewhat difficult to believe that over the four years of thinking about it you never weighed the pros and cons that people have been mentioning in this topic, like how it's a permanent decision. I know I certainly would have thought about it, and if after having done so my desire still remained unchanged for so long, I'd go ahead and do it.
And to all the people telling you that it's disgusting or whatever... don't let it get to you. I've always been a believer that the people in your life who truly care about you won't be so judgmental. Maybe it bothers them aesthetically, but they won't abandon you over it.
For a closing anecdote... my sister has beautiful jet black hair. A year or so ago she decided to dye it blonde, after having mentioned in passing for years that she wished she had been born with blonde hair. I personally think that her dyed hair looks unnatural and a bit ridiculous, but what I think about it doesn't matter. She's still my sister, and I still love her just the same. And the point is that it makes *her* happy to dye her hair, and it's her life to live. What's the point of living if you can't enjoy life?