FWIW, the ixus175_elph180 100a dump in the repository starts at FF800000 rather than FF81000 as expected by the tools. I uploaded a trimmed dump at
https://app.box.com/s/8lk4njec6nknpycovuqiyoiws3kexwo4This is mostly just for completeness, the 100c dump is correct, and the same port can almost certainly be used for both.