Why did you switch to TrueNAS Core?
After one year, any benefits of using that vs XigmaNAS apart from the pretty UI?
I didn't keep my XigmaNAS install up to date. I was still booting of a usb flash drive and that's not been supported/recommended for a while. Upgrading meant reinstalling so I figured I might as well install something else and try it. I looked at both FreeNAS and nas4free ten or so years ago and picked nas4free, which became XigmaNAS.
TrueNAS forums were a lot busier than XigmaNAS. Questions are answered more quickly, and more questions have been asked. It's a better reference and the TrueNAS documentation is better.
Why Core instead of Scale? I've been using FreeBSD since the 3.x release, so I've got a bit of a soft spot for it.
Any benefits of TrueNAS over XigmaNAS? Only the nicer UI. The way information that is presented is presented in a better way - the reporting tab in TrueNAS is very good. But I do miss stuff from XigmaNAS like the output of 'zpool iostat -vy 1' (or whatever Xigma's interval is) and 'zpool status -v', the output of both commands is shown in Xigma's UI exatly as is. in TrueNAS, as far as I know or as far as I've been able to find out, I have to run those from the command line. Which is no problem but it's an extra step.