1. The Allwinner chipset is 100% libre at this point [1], and they chose a cheap chip (the R8) so they could not have to subsidize their board unlike the Rpi Zero. If you want a more powerful board, buy an OrangePi PC Plus for $20.
2. "Full Fat" Debian is not very heavy, and you can easily disable what you don't need. The only "fat" is used disk space, which you can easily free up with a quick apt remove.
3. Can't comment much on the PocketCHIP, as I don't own one.
4. You want a secure way to get your OS onto your device, right? Even Signal for Desktop relies on Chrome, its virtually the only universally installable, secure way to distribute an application.
5. I have other A13 based boards and I've yet to encounter package breakage. The architecture is plain jane ARMv7, nothing specifically needs to be changed from the main Debian repos unlike the Raspberry Pi.
>At best (and without some serious work) the CHIP is destined to be a footnote amongst closed and partially broken Pi clones.
Its definitely far from closed, and it has decent software support unlike Pine64 and other failed boards, with the people behind the board writing eMMC drivers and working to build a better BBB. Compared to the BBB it is basically all there at this point.
Whether or not other cheaper boards like the OrangePi Zero wipe it out is yet to be seen though. The Pi ecosystem seems very caustic from what little I've seen with my Pi 3, reminds me of the Android modding community, hence why I've yet to build anything useful with my Pi 3.
[1] - http://linux-sunxi.org/Linux_mainlining_effort#Status_Matrix