Take this with a grain of salt - I haven't looked at the code in almost a year.
Hold sets throttle to RC_TRIM. That, in generally, wouldn't apply brakes but would depend on the ESC, usually it will just set you to "idle".
My understanding of ESCs is that if you pull back hard in manual mode it may well slow you down faster. If you set up HOLD to go full negative throttle (which would give you braking) you'd run the risk of flipping to full reverse.
A flag to select "HOLD" as RC_MIN or RC_TRIM would be helpful for anyone running a non-ESC braking system (I think the FarmDogg people have a system like that) - HOLD at RC_MIN would apply full brake.
This is fixed and now available. You can either get the latest firmware or I have also created a beta release which includes this fix.
The latest firmware build of the source code is always available at
For instance if your hardware is a Pixhawk this is the link you would use.
If your using MissionPlanner you can go into InitialSetup and select "Load custom firmware" and you should be able to upload it.
If you use this you are on the bleeding edge - no promises your rover won't be random ;-)
Let me know how you go.
From a couple of years of Rover testing experience, I have to agree with Mike Rover that switching to the MANUAL Mode and applying full reverse throttle is the best way to go in relation to going to the HOLD Mode.
The change from the AUTO Mode to the MANUAL Mode is extremely fast and being able to apply full reverse throttle has saved the bacon in many instances where the rover was headed towards an immovable object:-)