I think you should go for the Cybook. I personally have an iRex iLiad but I think you probably wouldn't be using most features on it (e.g. digitiser, etc.)
As far as your query about the quality of eInk screen compared to LCD/TFT, I can tell you that once you've used eInk you will not want to go back to LCD/TFT!
The difference is absolutely amazing. Most eInk devices will have similar performance for outdoor reading - which is great! The more light you get on the screen, the better contrast you get, just like normal paper.
Just make sure you don't expect back-light on eInk screens. It this regard eInk behaves in the same way as normal paper would - you will need a reading light to read in dark.