One SharePoint Online, Multiple AD.

Hello!

I'm looking for information in regards to using Multiple AD syncs for one Tenant. We have a case where we have a Tenant with an AD Sync towards a single AD. And we are looking to share our Intranet with other subsidiaries that have their own ADs. Looking through the documentation I came across this:

https://docs.microsoft.com/en-us/azure/active-directory/hybrid/plan-connect-topologies#multiple-forests-single-azure-ad-tenant

Looking at that article it seems like its very possible. 
But as I don't have access to any other environment to test this. I was looking for some input from the savvy o365 community!

Does anyone have some inputs as to why or why not this is a good or bad idea? Any experience with this that might discourage 1 tenant multiple AD approaches and to stick with only external sharing and Guest accounts? Any feedback is greatly appreciated!