However, for my Yaesu VX-7R, I'm not able to Upload. I was able to Download what I had in their before though. Whenever I try and upload anything to the VX-7R, the progress bar makes it to about between the "i" and "n" in the word "Cloning" above the progress bar every time... and then. KABOOM! Keyboard and Mouse input stops working on the Mac. Cannot even do a Force Kill keystroke (CMD-OPT-ESC). The power button does still work and brings up the Reboot/Shutdown/Cancel dialog box... but with no keyboard/mouse, can't really click on it. I have to hold down the power down till the machine forces turn off.
Yikes! That'd be a driver issue for the serial adapter. Nothing in userspace should be able to do that to your machine. Prolific had lots of trouble with their ported-from-XP driver on Vista for about a year after its release. Similar behavior would occur, requiring a total reboot to unstick the system. It was so bad that they posted something on their driver page that stated they didn't support vista at all. They seem to have resolved their issues now, however. Maybe there's an updated driver out there?
I have Best Buy brand (Dynex I think?) USB-Serial convertor for my 9-pin serial Yaesu cable. I've ordered a USB Yaesu cable from WAMA (or whatever that eBay site is), but won't be here for a few days. Here are the pertinent data, I think.
It will use a prolific chip, which appears to be what's in your Dynex. That means you'll likely have similar issues unless you find and install an updated driver.
FWIW, KeySpan seems to be best choice for MacOS users, but they're spendy.