I have used the Viliv x70. This is a full fuctioning pc tablet with built in 3g and GPS recievers. The screen is 7" and is sun readable.
I wouldn't call the x70
sunlight readable.
I sent it back as it was almost useless in sunlight - like most LCDs.
Maybe yours had some sort of contrast enhancing filter? I tried mine with an without one.
The format has great potential though. Just the right size, etc.