If you were building something new, wanting to use a high quality solder might make sense, but since you are only replacing the binding posts I doubt that the solder will make any difference at all.
Question about solder
I plan on replacing the binding posts on my amps. I have on hand some Radio Shack solder. I could order some of the Wonder Solder or Cardas solder however that will take a week to receive. Do you think the amount of solder required for connecting the binding posts will make a difference in using the Wonder Solder type vs the Radio Shack type?