One thing I do with Sarrs that seems to help is to add shredded pine-needles into the medium. I have never tried coffee on my Sarrs. A friend of mine used coffee on a Heliamphora recently I think, so I'll ask him about that and report back.
I have used coffee on my Neps for maybe a year and have seen pretty impressive results. I have a huge N. miranda that I've had for a few years now. When I got it, there were 3 pitchers on it, all around 6" tall. Over winter the pitchers died off, and the plant didn't do very much at all the next summer, making only 2 pitchers (despite having 3 growth points and being almost 3 feet across overall). Over last winter I found out about the coffee thing and started adding it to the plant about once a month. Last summer I put it out in the exact same place it had been the year previous. During this whole time I hadn't repotted the plant or changed anything besides the coffee, and I keep the plant inside in winter and move it outside in the summer so it's not like it was getting used to one set of conditions. Last summer I got more pitchers than I even bothered to count, all at least 5" tall.
Not a controlled experiment by any means, but it convinced me.