I have one (not itrip though) and the father-in-law has an itrip, I dont like the wireless personly...weaker signal (songs sound kinda muffeld) and the signal gets broken up sometimes as well as some cars just not picking up the sig.
Both of our wireless transmiters will not work on all of our cars. Mine will not work on the mustangs clarion headunit or the wifes alpine in her zx2. The father-in-laws will not work in there burban, and I dont think it works on his work truck either. That is the reason I am going with a direct wired rf modual, that and it will work with any mp3 player.