I've never used the Touring Plans fax service, but from what I've read over the years here, it seems to be no more or less successful than any other method for making room requests. You win some, you lose some.
For a recent stay at AKL I made my requests using the checklist during the online check-in process. My requests were met, and I was very happy with the room.
For a BC stay, I didn't think the online check-in form fully expressed what I wanted to say, so I called and had the phone CM add my request to my reservation. Again, my request was met, and the room was great.