My eyes are troubled by ereaders with lighted screens, too, arsingh1. I'm sure that for the majority of people, they look and feel excellent, but for folks like you and I, they're just not compatible. I find them only slightly more comfortable than reading from a tablet, regardless of ambient light sources.
I think that you should try a newer ereader that isn't lighted. I use one of the non-lit Kindles myself, and with a booklight it's very easy to read from. I also think that the Infibeam PI must be using older technology -- to the best of my knowledge, ereader screens don't fade in the sunlight any more, and have excellent clarity indoors in natural light.
If you've caught the e-reading bug, you should keep looking. It took me a while to find a good-enough paper replacement, too.
