Over the past few months I've made several inquiries about running Linux servers on ARM, specifically web services and email. After much consideration I moved my two domains over to a Banana Pi running a SATA SSD. I chose the Banana Pi over the similar and more popular Raspberry Pi2 for two reasons: Gigabit LAN and SATA. While the RPi sports a quad processor compared to the BPi's dual core, the BPi has native SATA2 and Gigabit LAN tied directly to the processor, whereas on RPi everything goes over the USB subsystem. Overall performance is quite good, considerably improved over the old Pentium 3 server it replaced.
In replacing my P3 servers, I've moved to multiple small devices so there isn't a single point of failure that can take down the entire network. Firewall duties are now being handled by a Ubiquiti EdgeRouter X. Ubiquiti runs it's own OS which is currently based on Debian Wheezy. File sharing is now handled by a Pogoplug V4 that's been hacked to boot Debian Wheezy. While the Pogoplug is under-powered compared to the BPi, it does have Gigabit LAN and a SATA2 connection along with 2 USB3 connectors for only $20! I've got a 1TB laptop SATA HDD sitting in the SATA slot to provide network file sharing. And though under-powered, it is quite capable of running Transmission (a bit torrent client) and MiniDNLA (a media server).
All my mini computers run a custom version of Debian based on Wheezy except for the BPi, which is based on Jessie. Most of them also have an ARCH Linux version available as well.
If anyone would like to try something similar, feel free to contact me with any questions.
--Dale