I'm using OpenWrt/LEDE 17.01.5 on 1 of my 1900ac(s) (vlan. openvpn, openssh, dnscrypt and my custom scrips)
+1 setup 
Can I use "sysupgrade -c linksys-wrt1900ac-squashfs-sysupgrade.bin" from 18.06.0?
Has anyone tested 17.01.5 with Xen or KVM? I tried upgrading from 17.01.4, but any time I save a file in /etc/config the file gets corrupted after restarting. On restart I see a brief filesystem error flash by on shutdown. I can easily reproduce on both Xen and KVM.