I still recommend the use of full-strength coffee (prepared with distilled or RO water) on Nepenthes; and my plants have responded very well to its use over the last few years (and far more effectively than any commercial fertilizer than I have ever used). I now use it biweekly or monthly without any issues to the live sphagnum moss; though I thoroughly rinse the posts a day or so after each application.
I have now started using it as of 2012 in a more controlled setting on a new group of seedling highlanders, including N. edwardsiana, N. hamata, N. macrophylla, N. rajah, and N. villosa; and I will post their progress in the months to come . . .