When I went to the vendor's firmware download page linked to in Need help identifying main processor for Roland synthesizer I saw this in the EULA:
- Restrictions: You may not make or distribute copies of the Roland Product, or electronically transfer the Roland Product from one computer to another or over a network. You may not decompile, reverse engineer, disassemble, or otherwise reduce the Roland Software to a human-perceivable form. You may not modify, sell, rent, transfer, resell for profit, distribute or create derivative works based upon the Roland Product or any part thereof. You may not export or reexport, directly or indirectly, the Roland Product into any country prohibited by the United States Export Administration Act and the regulations thereunder.
I should note here that the EULA also states the following:
This Agreement shall be governed by the internal laws of the United States of America and the State of California, without regard to its conflicts of law provisions.
Since we must agree to the EULA in order to download the binary, and since the OP wants to reverse engineer said binary, what should be done?
People typically do not read the EULA, so I would assume that in general they are unaware that what they are attempting to do is in violation of it.
I did see Are questions that involve DRM reverse engineering allowed? but I am unsure of how relevant it is.