Misc
The parser does not know anything about the underlying table and so cannot determine which datatypes to use. Instead the SQL merge statement is created with every data item using the nvarchar format.
This was chosen as most SQL types will implicitly convert from nvarchar.
Image taken from https://msdn.microsoft.com/en-us/library/ms191530.aspx?f=255&MSPPError=-2147217396
The types that do not implicitly convert (binaries) do not seem to be a good fit for this code due to the lengths of the data usually associated with these types. For the time being, binary types are not supported.