Why not use GDAL/OGR? You should be able to convert directly from your sde database to sql server. Here are some links that might help:
This one should give you the syntax for your sql server connection: https://alastaira.wordpress.com/ogr2ogr-patterns-for-sql-server/
This helps with the syntax for your sde connection: Migrating data from ArcSDE to PostGIS?Migrating data from ArcSDE to PostGIS?