Hi all, first post here ! Been using the MFC for 2 months in a non-AFX rig (the MFC controls a RJM Mini Effect Gizmo and TC G-Major 2), doing lots of gigs with 2 bands (one is around 30 gigs a year, the other one is 40 gigs in the 3 months of summer), and making extensive use of song/set mode, which actually was a main reason for going for a MFC-101 rather than any of the other available MIDI controllers.
Definitely ! The other day I had to program a couple of presets on the fly between soundcheck and show, edit a song and add it to the set in use, and doing it without the offline editor is much slower and requires writing down presets, song and song position numbers, which made doing a simple edit much more annoying than it would have been with the editor.
As a side note, after testing both editors, I eventually went with Fedit. Both are good, I like MFC-Edit's user interface better (it's easier to program presets with it IMO), but like Fedit better for editing setlists, since you can drag and drop presets and songs into sets instead of having to choose from scrolling lists (I use around 40 presets, into 60 songs, into 4 setlists), so in the end, Fedit was better for the way I use the MFC101. YMMV though, it's a matter of personal preference.
Props to the creators of both controllers btw, it makes a very good tool even better !