I had a second so I did this test for you here's what it does for me:
I exported a sample 30 sec. clip with the default MPEG2-DVD settings then exported again and while in PP I selected the file name link, and re-selected the file I had just save so that I would be prompted with the replace dialog. I was, hit ok, and it opened AME. I hit start and it encoded fine the weird thing is, it didn't replace the file, it added an _1 to the end of it.
OK, just to make sure I wasn't going crazy, I did it again and got the same result.
SO, next, I exported the same clip but this time I waited until AME opened and then from within AME I selected the file name link and selected the same file name and again was prompted to replace file. I hit encode and it did the same thing but of course, it was a _2 it added this time.
I guess it's better then a crash!