I've been having fun.
I systematically thought about add6 chords and m7 chords. I can't really play add6, but I know all my m7's. And they're the same. So all I have to do is remember which add6 is which m7. The one exception is that I play A6 differently. I learned to play it in a typical blues shuffle: A, A6, A7. The A of course is 2100; the A6 is 2120 and the A7 is 2130. Those 6's and 7's obviously are lacking their dominant degree, but they sound good. The implication for this is that if A6 is 2130, then F#m7 is 2130 which is a godsend because F#m7 is regularly played as 2424 which is a very nasty chord. That means that I would play the F#m and F#m7 as the same thing. That might not work in all cases, but I'll cross that bridge when I come to it. This isn't at all unprecedented in my playing. For example when I need to play F#maj7, I play Bbm. The Bbm is a rootless F#maj7. Rootless chords can sound a little etiolated but the context will be judge of that and how often will I need a F#maj7?
Why is F# such a pill?
Speaking of being a pill, I just stumbled upon a video purporting that music theory is not hard (a thesis I whole-heartedly endorse) but then the person in the video quizzes the viewers with how many keys there are? His answer is 30! I thought: dude, you're being a douche by including the enharmonic keys. The practical answer should be 24 because no one is going to play in Cb or Fb or even use G# with its 6 sharps and one double-sharp when Ab, its enharmonic equivalent, only has 4 flats.
Anyway, that brought my mind back to F#. Gb and F# are enharmonically equivalent and each has 6 accidents. Therefore there is no way to prefer one to the other. However, I have been told that Gb is more common. However I think it would depend on what you're doing with the key. If you're just making a rather simple melody, then either would be okay. However if I were going to play some modal harmonies, I would definitely write them in F#. For example if your melody was in Aiolian, a very popular mode, you have a flat III, VI, and VII. These 3 notes are naturally sharped because of the key, so playing them in Aiolian would be easy: A# becomes A, D# becomes D, etc. If I conceived of this in the key of Gb, it would be a little more awkward because I would be flattening a flat, which any musician worth his weight in tabouli can do...however, since we're talking about ease. F# is easier in this context.
The last thing I'm doing right now, is struggling with a new Am7 fingering. I dislike the typical 0000 chord, so I usually play it 2433. I saw a video of Stu Fuchs playing both the E and A strings with a flattened middle finger and I was very intrigued because I cannot do this at all. I normally use the index for the '2', the pinky for the '4' and my the two middle fingers play the two '3' frets. One of my favorite sequences is Eb7, D7, Gm7 and I play the Gm7 with my index finger barreing the E and A string and my ring finger fretting the C string (0211). But transposing that shape up a note is impossible for me. The index finger isn't part of this issue; it is just replacing the nut and will barre everything and only be responsible for the G string. The antogonists here are the middle two fingers. The issue is that they aren't independent. However I need one finger to lie flat while the other finger remain arched. I'm going to be working on it, because this is for me a very important movable chord. If I can master the new fingering, it is eminently more movable.