After my gedcom comparisons comes up, I look through the ICW tab, and then DNA segment tab. I click on the circle arrows next to the profile's name - generally the largest segment. This will take you to the Chromosome Map. If you click on that person's name, the gedcom should still be there, but if you have entered any information in the other fields in the Relatives screen, it won't have flowed through, so I enter the information, notes, ANC family tree URL, etc. in this screen and then I update all segments across all profiles. You may choose to update only a certain segment (such as the one your are in when you are entering the information) or only the current profile, depending on your research interests. Since I've got three profiles set up and all my mother's matches match me and my brother (except those so distant to her that she didn't pass along that DNA to us), this option works for me.
In any case, the match's record from the Chrome Map is the only screen that has the update button. If you don't update, and you share more than one segment with the match, you'll have to enter the gedcom and notes manually to that match's info screen on each segment you share.
I guess you could say that in Genome Mate your matches are "segment-centric" and the information is "segment-driven" rather than "profile-centric". I hope that makes sense :)