This wont harm my Droid X in anyway right?
Sent from my DROIDX
No problems that I've ever had after changing the codec. The codec is just an method that the phone uses to convert your voice into a digital signal that it can send. I don't know about the value of changing the codec to any of the other choices, I just know that the EVRC-B was much better than EVRC. It's kinda like compressing your file with ZIP versus ARJ verus GZ, etc...
So, while I can't definitively state that there won't be any harm from this- I've set mine to EVRC-B for the past month and have noticed no differences in my phone operation. Battery life is still the same, no additional crashes, no excessive heat, etc..