I have my home server/router running Arch, update maybe 5 times per year, only one time a non-critical service(redis) failed to start due to a default config option change. I originally meant to run Debian on that, but when I bought the hardware, it's pretty exotic for Debian's old kernel, and Arch ran great.
I also have a Pi2 running Arch ARM at my mom's house, doing one or two updates per year when I visit her, also failed only once, and that's because of a corrupted SD card.
I'd admit I'm usually a bit nervous typing pacman -Syu on those two, but it's doing surprisingly great.
You’d probably have less overall risk on upgrades if you actually did it more often. A couple of times a year can result in quite a jump when using a rolling distro
I also have a Pi2 running Arch ARM at my mom's house, doing one or two updates per year when I visit her, also failed only once, and that's because of a corrupted SD card.
I'd admit I'm usually a bit nervous typing pacman -Syu on those two, but it's doing surprisingly great.