I've been playing with Family Tree Maker.
I do like the ability to "merge" sources from Ancestry.com into my Family Tree Maker database.
I though only merge sources I am 100% certain are the same person and only merge census records, passenger lists, SSDI entries and other entries coming from actual records. I do not merge GEDCOM files, or any other sources of that type. I'm VERY selective about what I merge, let's just leave it at that.
This is the screen that came up when I started to merge my grandfather Neill's SSDI entry with his entry in my Family Tree Maker database. I had his birth as 29 Oct 1903 in Walker Township, Hancock County, Illinois. The SSDI provides the same date of birth, but no place of birth. I wish Family Tree Maker did not originally suggest to "add source only" in this instance. The reason is that the SSDI indicates the date of birth is 29 Oct 1903, but it does not provide a location. Adding the SSDI as a source for the birth of 29 Oct 1903 in Walker Township, Hancock County, Illinois, implies that the SSDI provides the place of birth, when it did not.
I'm going to choose "make alternate" on this date of birth for Grandpa, even though it is the same date I already have. I never want to indicate a source says something that it does not or that it is more complete than it actually is.