Only difference some “power” users might notice is not being able to update to any kernal. The kernal will be what ever is the lxc host server is using. When it gets updated, all lxc clients get updated since they are all using it. There is no separate kernal for each machine.
I’ve moved from offering kvm to lxd becasue its much simpler to setup and replicate machines.
To make a point about PualVM quotas, if lxc/lxd is hosted on zfs file system, quotas per machine can be adjusted on the fly through zfs. Similar goes for adding memory or cpu. Can be added/subtracted anytime, live, no reboot.