Sybase ASE to Microsoft SQL Server Replication

I am currently working on several projects to migrate legacy applications from a Sybase ASE (12.5 and 15.0) to a Microsoft SQL Server 2014 platform. There will be a need to replicate data in both directions while the old and new applications are being developed. I was looking for advice regarding how others have approached this problem. Some ideas we're looking into: 1. Sybase Replication Server (Expensive) 2. Third party Apps (Not sure if it will be stable?) 3. Custom Stored Procedures in Sybase for Update, Insert and Delete and configure those to be called when the data comes in. (Reliability and difficulty of supporting)