The really early back-lit Voyagers had a high-pitched whine that could be heard, the solution was to just turn the light down. They solved that with a new version; I also understand that light could burn out after several years. Some people have reported problems with the trackpad, but that seems to be pretty rare and easily fixed or worked around (I rarely use the trackpad myself). I have a 2003 Performer (no backlight) and it has worked fine since I have owned it.
I've owned my Voyager since they first came out in 2003 and I have never heard of issues with the digital board.
I bought my Anniversary Edition in 2004 and I have never had a problem with it or the digital board. I heard that some later models had problems but I think most of them got the digital board replaced for free.