Just wanted to share with you that I finally purchased In Ear Monitors for monitoring my live performances. I didn't want to spend too much money in a professional wireless system, so I decided to buy a Sennheiser IE-3 model in a german online shop. This is exactly the same product sold by Future Sonics under the name "Future Sonics Ears" (same exact specifications). The best news are that the "Sennheiser price" (90 Euros) is less than half the Future Sonics online price ($198).
Althought I still didn't use it live, I'm quite happy with the sound, significantly better than the walkman cheap headphones, specially the bass response. A proper adjustment to each ear (I found it easy) is critical to achieve a good bass response, but once it's in the right place the sound is great. Only thing I didn't like: why do these guys make the cables so short?!
-- José.