The Java Client Library interface supplies String objects to application code,
hence, using Lightstreamer to transport binary data would require that application code could encode data into Strings in the Data Adapter and decode the received String data on the client.

Note that the Data Adapter interface also allows you to specify the content for a field as a byte array, but that implies a conversion to a String through ISO-8859-1 encoding, as clarified here.

By the way, binary data support is available on the Flex Client Library; details here.

Anyway, the check for unchanged values cannot be disabled.
Note that the check only involves distinct objects received from the Data Adapter. If your item is in MERGE mode and the Data Adapter does not resend unchanged objects upon updates, no checks are involved in those cases.