ACI Brownfield to multi-site

[brlehigh]

Good day,
I have an existing production fabric and I'm spinning up a Greenfield DR fabric.  I am worried about potential service impact(s) to my production fabric when adding it to multi-site.  
The "tl;dr" of my post is: Is there a service impact when I initially add my fabric to Nexus Dashboard Orchestrator and again when I enable Multi-site and apply the needed infra config from NDO?

I've read through several deployment documents but I found the following bullet-point in Cisco ACI Multi-Site Architecture White Paper :
When a site is added to a Multi-Site domain, the BGP RID is modified on the spines that are configured as BGP speakers. This may cause the re-establishment of intra-fabric VPNv4 adjacencies between the spines (configured as RR for the fabric) and the leaf nodes, with consequent impact on north-south communications. Therefore, it is recommended to perform the addition of the site to the Multi-Site domain during a maintenance window.

My fabric is configured as network centric with the majority of the gateways residing outside the fabric.  Will there be a service impact to any layer 2 traffic in/out of the fabric or is this above warning just for layer 3 traffic (l3out)?

My Greenfield / DR fabric is already up and added to NDO with multi-site enabled and have it connected to the ISN.  I haven't done much beyond day-0 config on the new fabric, with the intent of stretching the tenant and a few dozen EPGs from the prod fabric.

Are there any other caveats that I should be ware of before adding a production fabric to NDO / Multi-site?

Thanks

[brlehigh · Accepted solution]

I'll go ahead and reply to my own post to close the loop.
I enabled multi-site on my production fabric this morning.  I did not experience any service disruption when adding the site to Nexus Dashboard or when enabling "Managed". 
When I configured the infra for this site via Nexus Dashboard Orchestrator and deployed the configuration, I did see the BGP processes bounce on my prod fabric, however, I did not notice a service disruption to any of my traffic.
Again, we do not do a ton of layer 3 north-south traffic from this fabric, so it might have been more impactful had this not been the case.  I did have pings going throughout the window and did not experience any loss.
With that said, I would still recommend performing this process during a maintenance window.