I used FG-7 considerably in the early 1970s and found it flexible, versitle, and economical. I also used in through the 1980s for BW copy negs of vintage photographs, using it at 1:30, with sodium sulfite, on KB14, mostly.
At present, I have two new (plastic) bottles and plan to revisit an old friend, but have not yet gotten around to it. Unfortunately, the data sheets I took from those neat glass bottles have long disappeared. Some may remember the charts with film groupings in roman numerals, with dilutions and times, both with and without sodium sulfite. I wrote to the current owner of FG-7 for their free data sheets, but they are not half as much fun as the old ones. It can be used as a non-solvent developer for greatest sharpness with fine grain films, and with 9 % sodium sulfite for faster films. Somewhere in my notes I have an article by Bill Pierce about using it with TRI-X.
I always found it less "finicky" than Rodinal. Oh, yes, and you can process up to three batches of film in the same working soup, if done the same day, without sodium sulfite, and increase 10% for each batch.