Is it possble to change the web domain?

I was wondering if its possible to change the WEB_DOMAIN of an instance (from the root to a subdomain) after its been installed without breaking existing federation by following these instructions. Will that have any side effects on the existing instance?

Also, are there any downsides presently to having a different WEB_DOMAIN? I know that page mentions issues with v1.3.X but they should be all resolved, right? Will federation with non-Mastodon ActivityPub instances still work?