Which technology to synchronise SQL Server and MySQL data?
Given the above comments, I'd recommend going with an SSIS package. 
If you go with the linked server option you are injecting database dependency between the replication and the MSSQL server objects.
Linked servers are also a security liability, anyone with sufficient permissions on the MSSQL database can access the target database on the linked server.
Choosing SSIS gives complete control over the datasources, execution, scheduling and effectively decouples the data transfer from the actual databases.