I did the same as you. True, as you state they will not know what was not in the GEDCOM that was in your original files. But if you want to experiment and find out what they are NOT getting why not try to install that GEDCOM somewhere on your drive(not to conflict with your existing data if you have FTM)and compare it to your original. Check to see if all sources are there, similarly try it with text files. I have done that. And, I have found lots of sources not there that are in my UFT database, also lots of text files did not appear in the GEDCOM.
I have tried all versions of UFT GEDCOMs just to see what I get. And I tried Family 5.5 just as a curious venture. Not surprisingly, it surely did not work propperly.
So, in a nutshell, not one of UFT's GEDCOMs work properly.
And if someone out there can prove me wrong I will humble beg forgiveness for the tones of my messages :-)