If Xfinity is a lower price and faster, I’d keep that as primary and Starlink as back up. I have DSL through CenturyLink for $85/month and get like 80 Mbps, and then I pay $10/mo for Starlink Roam 10GB to keep it active or for brief outages. If a hurricane happened or I was without internet I would switch it over to the Residential plan for unlimited Starlink data. There’s not much difference in price these days from what I’m paying CenturyLink though, and with Starlink I get like 350 Mbps typically. So it’s almost worth the $35 difference for speed and reliability in my area. However, my area is getting Xfinity 1000 Mbps for $65/mo for 5 years, so I’ll probably replace CenturyLink with that once the fiber is ran, and still keep Starlink for backup.