Hi,
I've been using the tool for approx. 1 month and, honestly, I feel even more motivated to work on my game =]
The only caveat (for me) is that GMS 1 doesn't correctly reload an object where I added events by typing #event... directly. If the GMS saves the project in this state it ends up trying to overwrite the contents of that object with "nothing".
Fortunately, GMEdit asks if I want to keep the current content, but it always gives me a fear of clicking wrong and losing progress =P I've worked around this by avoiding performing actions in the GMS editor that force me to save in it (basically anything other than editing code) while I have "pending" content in GMEdit.
I know this isn't a flaw of GMEdit itself, but it would be nice if there was a way to force the program to keep its contents (something like a "always overwrite changes to files" config).
Moreover, an option to suggest/autocomplete text in strings based on the content of strings in the project would come in handy.
Congrats on the tool!