I'm a believer.
I gotta say I used some cheaper two part hardware store variety teak cleaner on a 100-year old ash seat, and after about an hour of some soaking and scrubbing the seat looked like new. I was very happy with the results. You wouldn't believe the amount of crud that came off...oh wait, that is "patina"!!!! Kidding, I really do like the look of the seat now.
Fitz.