Thanks for dredging this thread up. I do hope we can be civil! I don't enjoy the tendency for those that are unwilling to sign their name are more likely to be uncivil. PS: the Boogy Man hasn't gotten me yet. Do consider standing behind your posts with your names and reputations! I do.
Since there are several reactions in the mash that alter the mineral content of the raw wort compared to the starting water profile, I've long recommended that both mashing and sparging water be treated to approximately the same ionic content. The big difference is that sparging water MUST have low alkalinity and that might alter its other ionic content somewhat.
But with this said, its still OK to add minerals to either the mash, sparge, or kettle as desired. Just recognize that the ending effect of those additions will vary. If you like the results of adding the minerals a certain way, RDWHAHB. As long as the mash pH falls in line, its OK.