First off. an "is it worth it?" question is one only you can answer.
Now, a couple of points to consider...
You have referred to the part as the "Decocker". IT's not. It is the SAFETY.
it may be referred to as a "decocking safety" by some folks, but it is the safety. It just happens to safely drop(decock) the hammer when applied. Look in the owner's manual parts list, you'll see the maker calls it the safety.
And that is going to matter if the dark day ever arrives that you wind up in court over anything involving that gun.
Any lawyer (and prosecutors ARE lawyers) worth their fee is going to seize on the fact that you had the gun modified, and try to use that to convince the jury that you were in the wrong.
Turning the safety into a decocker only (because its your personal preference) in today's legal climate isn't a good idea, in my opinion. Because, if you ever wind up in court, the jury is going to be told that you "Willfully and deliberately deactivated the safety on the pistol, making it easier to shoot!"
And the rub is, that's not a lie.
It doesn't matter what you intend, or what you believe, in court, it matters what someone convinces the jury to believe.
Turning the safety into a decocker only does literally defeat the safety, IT no longer works as designed. The fact that the gun is mechanically safe to carry with the hammer down and the safety OFF doesn't matter. YOU disabled the safety!
Shooter will understand that your big concern is you don't want to risk having the safety go "ON" when you need it off. The general public does not know this. And they are who is going to be on any jury. ALL they will know is what the lawyers tell them. And if there is even any chance at all of the argument gaining traction in their minds, the other side WILL use it against you.
They can take your modified gun, show it off, tell the jury how you intentionally disabled the safety. The Police don't do that, the Military doesn't do that. Only someone actively seeking a shooting would do that. They'll do their best to show how your disregard for safety and your overall "gunfighter" attitude created the shooting, etc, etc, etc...
is it a big risk? not likely, but needing to use your pistol defensively isn't likely, either....Now, someone will come along and demand some proof, some case where this was done and someone went to jail because of it, and since I can't provide that, they'll claim its not worth considering. Maybe its not, but I'm not going to put myself in a position where I might possible be the test case. Won't recommend you do that, either.
If decocker only is important to you (and it must be if you're considering modifying the gun you have), I would say, get a different gun. Get something that works the way you WANT and are comfortable with, the way it comes out of the box. Sigs are good guns, (I personally prefer them to the Berettas) and have decockers, not decocking safeties.
Maybe I'm making much ado about nothing, but what if I'm not??
Go watch MY COUSIN VINNEY, its one of my favorite "court" movies. If you can get past the R rated language it's an excellent (and humorous) telling of how circumstantial evidence and the phrasing used in court can create a totally false, yet believable, recounting of what actually happened.
It's your gun, do what makes you happy with it.