If I was gonna build an arm nas I would go with something like the odroid hc2 sbc+enclosures which are cool. but the best thing about the cm4s is that you can design your own weird carrier boards and get a bunch of new projects like this one.

as for their compute, I’ve been running a 4gb module as my openwrt router and firewall with multiple lxc containers. its been handling everything very well and have yet to run into any performance issues.