They look like they use the same lens and frame as the old Raven NVX goggles, which I used for years until recently. The lens has good clarity and periferal vision and they never fogged-up on me. Unfortunately, it seems like they have ceased production on the auto-tinting lenses, which always worked quite well for me. I never understood why they didn't catch on. The standard thermal lenses can still be found, but from what I've found, most places just seem to be clearing out old stock. Kingman just doesn't seem to show much support for their goggles anymore. I miss the old, independently-owned Raven. . .
Sorry, back on topic: I can't comment on the rest of the mask, but I bet it's decent. I wouldn't recommend them, though; you'll probably end up having to buy a whole new mask by the time you need to replace the lens anyway.
I've heard mixed things about the Echo's. I tried a set on briefly and they seemed pretty comfy and I didn't notice anything bad about the lens clarity. But I've also heard that the fan isn't all that great. I've always liked the uncomplicated look of the Echo's and felt that they are one of the few masks that doesn't look silly with the visor installed.