It would take someone a very long time to convince me that the type or condition of the strings contributes to fret wear, I personaly think thats its the way a person plays the instrument, some people play so hard it looks like they're trying to push the string into the fret board, and a friend of mine plays in a way that it looks like he's not even touching the strings, his hand just glides up and down the fret board with a very lite touch and every note is clear, ( he plays a 72 precision that he bought new and he plays it a lot and the frets look a lot like the day Fender installed them ! ) add to that the amount of time the bass is played, fret wear will not be the same for a bass thats played 2 or 3 times a month for a couple hours compared to a bass thats played for 25 or 30 hours a week, and throw in the fact that there's a good chance that not all frets are made with the exact same material, so if your the kind of musician that plays the crap out of your bass because its your most favorite thing to do in life, and you have dressed the frets, and filed them, and worn them out completely, and its your cherished bass, than go ahead and have it refreted and carry on, just carry on !