Ok,. I know you have seen many of these, there were dingoo, gamepark series, the other chinese android (yinlips, jxd, etc), the overpriced pandora,. and you'd tell me who needs this when my PSP plays emuls or we have tablets and phones.
But if you have followed the specific community, homebrew/emu handheld, mainly on gamepark/dingoo, there was stagnation, Pandora failed to reach people, the chinese androids might be not bad or some say they are but the community didn't know where to move when 10s of them were released (the obscure handheld boom), so the main community wanted the next step to move on. And the next step seems to be GCW Zero for me. Which I really want to support.
So, just for your information, there is a kickstarter (http://www.kickstarter.com/projects/gcw/gcw-zero-open-source-gaming-handheld) available. With 135$ you get the console.
Main site (http://www.gcw-zero.com/)
youtube playlist (https://www.youtube.com/playlist?list=PL_HMl00OlQX9DoItQPN2MemZkgn_eSd3e)
I hope they make Amstrad emul for this soon too. But as I see perfect C64, Amiga, SNES already, I think it's coming. This one seems 3x faster than the latest Caanoo and less expensive. I know, some people find the price too much for the specs they consider low (320*240, what? But your NDS had 256*192 (just like speccy :) and the games were still awesome) and it doesn't seem as innovative in design as Pandora would if it went kickstart at the time they started, it doesn't look so slick like Ouya or I don't know what,... but GCW!!! The community here..
Ok,. just to inform. If you love the open handhelds and you'd like one or you just like to support or are curious, see the links.
Gryzor already done a news about it.
It's the same chines pcb than others listed in your post. No interest.
Spera mate!
You missed this: http://www.cpcwiki.eu/forum/other-retro/another-handheld-on-kickstarter/ :)
Sorry didn't see it even though I did a little search.
I'm still on my Dingoo... But i lost one of the shoulder button and i'm no good a soldering such tiny pieces...