If vizplex would have an advantage over the eink used in the iLiad, i would agree, but i have seen quite a few iLiads next to quite a few vizplex screens, and the iLiad is sharper, the black is blacker. Just the screen refresh rate is slower.
So i hope for an improved device with the next gen flexible display. Those do not need a glas layer for eink anymore. Although the wacom might need one still.