Yes, I have. I followed the instructions in FWW 126 (K. Rodel) and it worked like a charm to fume QSWO. I had a small piece - built a tent as described and used household ammonia (much debate from what I read about household strength versus industrial strength-I wasn't excited about the cost/complexity/safety of using concentrated solutions, so I tried the household variety and it worked fine) and worked outdoors. As described, the piece turned grey/green, and it was not until application of BLO that I got the desired effect. Also, I placed sample boards in with the piece to test at intervals - this worked well to gauge the degree of color change I wanted. If I recall, I had to wait 1-3 hours to get the amount of coloration I wanted. Very straightforward. One thing that surprised me - as the "tent" was pretty small, I leaned various pieces of the project against one another. The "exposure" of different sides, and of the somewhat obscured areas underneath, was apparently different, and these parts actually ended up less colored - I had anticipated that the fumes would evenly coat all surfaces. The degree of variation was not very substantial, though, and not a problem. Finished off w. shellac. I'd do it again any time. Also, BTW, Jeff Jewitt at Homestead has a stain/dye schedule that is supposed to mimic fuming very closely without any exposure to ammonia.
Good luck!
Don