In recently merging my Ancestry.com GEDCOM with my Legacy file I discovered that Ancestry.com accepts only "abt" for approximate dates and in Legacy I tend to use "cir". This was holding up merges, so it was time for another search and replace, this time in the "Dates-birth" field. I replaced all "whole word" "cir" with "abt".
I was careful to make sure the "replace only found text" was selected or else it would have turned "cir 1900" into "abt" with no date at all!
This resulted in over 23,000 replacements for my file.
I then repeated the same search and replace with the "Dates-death" field. This resulted in about 350 replacements in my file.
I repeated again with "Dates-Marriage" which resulted in about 750 replacements in my file.
In the future I will try hard to use "abt" when entering dates in Legacy, because someday I may lose my mind and try to merge my Ancestry.com and Legacy files again....