I know when using VOX for digital (tried it with APRS) the volume settings can be very tricky.
I used it successfully with? breadboard Mobilinkd TNC with a bluetooth interface with my phone and cable to the UV5R until both the UV-5R and the TNC unfortunately died due to some electrical issues with my car.
They guy had a heck of a time and pointed out some serious concerns using Baofeng. Mainly volume level, stability, and mostly unpredictable expectations from radio to radio. This goes to the "hardened" comment I had.