What are the implications of changing the SQL Server Service Logon Account? My default instance currently uses Network Service. I want to change this to a domain account. Are there any implications?
If you are talking about the immediate impact, then the service will need to be restarted in order for that change to take effect. As per TechNet:
Using a domain account as the SQL Server service account is considered best practice, so you are making a step in the right direction.
For further reading, the TechNet reference on Change the Service Startup Account for SQL Server.