First, be aware that the SATA port hangs off USB, so it does have performance limitations. I'm not too aware of what installers are available for the H3 cpu, but you can certainly start with a vendor supplied Linux image and compile an updated kernel. Some support elements are included in mainline kernel, some elements must be patched in.
http://linux-sunxi.org/Linux_mainlining_effort

As far as application, I'd recommend starting with getting MIDI synth working and go from there. That will give you a reference point to compare performance with other platforms.

Also, don't count on Raspberry Pi compatible images being compatible. Although the CPU architecture (Cortex A7) is the same, pretty much all the peripherals are different.

I've had three Raspberry Pi. One was the first model B (256Mb RAM), other is a model B with 512 Mb and the last one is a Raspberry Pi 2 model B.

I've tested it with Retropie, and it works fine. All 8 bit systems works fine, 16 bits usually works well (sometimes it stutters) and even some PSX games can be played at full speed (with some overclocking on Raspberry Pi 1).

One of those machines (the model B with 512 Mb) is my download machine. Currently it runs:
- Raspbian Jessie Lite. X-Windows is not needed on this machine, so a "minimal" Raspbian image helps performance.
- amule-daemon and transmission, so that machine can do downloads unattended (I'm thinking about using pyload too, and it has httrack to crawl websites).
- ownCloud, serving as a mirror for some documents (this server is NOT connected to internet).
- minidlna, to serve as a media server for my TV.

It runs 24x7 without problems, and only when it's transferring too much data the minidlna server stops working (it has happened only twice).

The only problem I've had is that it has "burned" a Samsung microSD card (it uses that SD card as system, and a pendrive for storage... that faulty card can be read but not written). And that reminds me of that eMMC installed on the Orange Pi. Is that the boot device? In my Raspberry Pi I can change the SD card if it becomes unreadable, but if that eMMC is the boot device and it fails you'll probably end replacing the entire board.

I've had a model B+ running continuously since 2014 and it's still going strong.

Thanks for all the input. I am really looking forward to test the board out with a Linux distro first.
I think I will try that Lubuntu wich I can download from their site, then the Debian server.