eInk's primary advantages are power (and only if your idle period is long enough; if you have to update it with any frequence you're going to lose pretty soon to a memory LCD); and angles/polarity (specially compared to LCD), which some people also claim produces less headaches.
The company also doesn't exist and only produced 10" 1024x600 screens, which are barely usable. If you know of another usable product, or have anything to back up your claims, please do share.
I also have the Metawatch. These are purely reflective, not transflective. They boast whopping 20:1 contrast ratios -- https://www.sharpsma.com/products?sharpCategory=Memory%20LCD... . Even at its best days (carta) eInk didn't reach that 15:1 https://wiki.mobileread.com/wiki/E_Ink_Carta , and nowadays it's more like 10:1.
I've owned two devices with them so far, and quite frankly the newer one works just as well (if not better) than E-Ink outdoors but still has a backlight when necessary. Also, it can display color and smooth motion. The minor downside I see is the lack of an ability to display an image with zero battery consumption, such as on E-Ink, but the consumption is still so low that the transflective LCD watches can last weeks with an always-on display.
As noted, we already have e-ink phones that can do both colour and video[1], while there is some ghosting it's getting to the point of usable. Just need a big display to match it.
1. https://www.youtube.com/watch?v=EakZQlPvgIY&t=9m35s