We are about to launch a new .NET core service and I've been working with .NET core for about 2 years now. Not only is Linux not a second class citizen (it is the easiest platform to run on and scale), but dropping support would make no sense from a business or technical standpoint. Microsoft is making a ton of money by supporting cross platform.

We aren't using SQL Server, but I've used most of the big RDBMS and SQL Server is the best. It just tends to be more expensive.

So far it has been anything but a "pain".