I have 80 or so existing networks in my Meraki dashboard. To date I've deployed many Meraki MS and Meraki MR all without using config templates. Generally I have been adding new networks and copying from an existing network.
But now I have started adding Meraki MX SD WAN devices and templating might be useful but I have some questions about it.
First - how can I limit what aspects of a new MX are copied from a template? For example supposed I setup by hand a MX with specific firewall, content filtering and threat settings. I add that into an existing network. Now I have my second MX and I want to add that to another existing network and I want those three attributes to be the same as the first. How do I accomplish this? When I ran a test it seemed to want to copy everything from an existing site.
Second when I tested copying from an existing network I get the warning "Group policies and other client-specific policies and authorizations on the target network(s) will be permanently removed upon binding." Could that mess up any of my existing switches or access point settings in the target site? The lack of granularity and lack of a preview of exactly what's to be modified is concerning.
Before planning for templates, make sure that you understand what they are and how they work. Especially, look at the way IP addressing is done. If you come from a traditional setup with summarized networks for your branches, you will be a little bit "shocked" how addressing is done here. And you should be aware that every change of the addressing in the template will renumber the addressing in the networks.
At least for me, these are too many drawbacks and I only use individual networks. For automation, the Meraki API will help you to keep your networks consistent.