Actually, vizplex has less contrast

It has a contrast ratio of 7:1 whereas the previous material has about 8:1.
But the refectivity of vizplex is about 40% while previous e-ink material had around 32-35%.
So all in all, its not "that much" of a difference. But its a step. Since its brighter, it might seem more contratsy to some people. I like that ist faster though.