I was able to connect to the radio and download the contents. (So I have to assume there is a problem with pyserial in the package I downloaded... )
Hmm, I dunno about that. I think it's more likely that the USB serial driver that's handling whatever chip is in the radio isn't quite right on MacOS. The python-serial library just handles opening the device, attaching a file handle to it, and setting the baud rate.
Here is the bad news, the linux version doesn't show any of the memory locations I downloaded, they are all 0.0000 and grayed out. When I save the file, I can run strings on it and see that the data is indeed there..
Well, not having anything to test with, I really have to plead ignorance and hope that Vernon can offer some insight :)