A better fine grained approach for the binary diffing should be able to detect binary changes with delta offsets.
This kind of diffing is the same algorithm used by the GNU diff utility applied on text based files. The fast hacky approach in radare is done by exporting two binaries files as one hexpair per line ascii files, and then use the GNU diff with these two files to get the delta calculations.
This is the default bindiffing engine use by radiff. You can force the use of this with '-d'.
radiff -d /bin/true /bin/false
The other approach is done in C++ with better performance and can be used by appending the '-e' flag.
radiff -e /bin/true /bin/false