Just a quick note. I have a Basecam Handy gimbal. It's running the 2.68b7 firmware. I've been controlling it through serial. I can set the BAUD rate to 256000 through the GUI but then once I write settings I can no longer connect to it through the GUI. I can still connect to it through serial using python at the new BAUD rate. If I want to use the GUI, I have to press the menu button 12 times to reset the BAUD rate to 115200. Seems like the GUI can't handle the 256000 BAUD rate. No idea why.
Helo, GUI use auto-detection of baud rates, so it needs some time to switch to new rate. Then it remembers last used rate and next time connects quickly. You can disable auto-detection and set an expected rate in the GUI, File - Settings.