hello
i'm using one of those as a local boinc client / ftp / file server ( the a20-lime )
compared to RPI:
- better documentation if you want to make some mods : i've added an ultracap to the AXP209 power management IC, so it will keep my custom LiPo charging parameters
- 1 cell LiPo charger integrated - it will run the entire board, including the hard-drive form one cell
- linux-sunxi mail list and community is quite active
- more IO's if you need them
- native SATA in the A20 chipset, so no usb-sata converter is needed
- gigabit ethernet on the A20 lime2 boards(some revisions are not working properly)
- seems very stable: with the latest armbian releases i've never had a crash / freeze
- lower power CPU's -> it will get sluggish if you need some serious processing
- the video stuff is not working under mainline kernel - at least not in the official builds
- it's not able to push the SATA interface to it's limits - the A20 chipset is not able to
- some things from the mainline kernel need to be better organized - especially the device tree configuration files.
the good part is that you can submit patches and the guys will accept them quickly if they are correct, etc
=> if you want a low power headless server then it's ok, with the advantage of an included UPS - the LiPo charger part
if you want to use it as a media platform, then no, i don't think it will make it, in that regard a rpi3 is much better.
for example it's not usable as a SDR radio decoder, a rpi3 can do the same stuff with 20% cpu load.
if you need extra info i can run some benchmarks when i get home.
i have a sata hard-drive and it's in a 100Mb network - so i can try pushing it to the limit
a list of what's working in mainline kernel:
http://linux-sunxi.org/Linux_mainlining_effortand a link to armbian builds(for my board):
https://www.armbian.com/olimex-lime-2/