Speed mode with zero speed hold

Hi! I want to understand if it's possible to extend / make new mode something like speed mode with zero speed hold. 

What I actually mean. Previously I've used Odrive ESCs and bunch of other china controllers that have speed mode. The behaviour in speed mode in this controllers are that when the zero command is equal to 0, the esc try to "hold" zero speed as much as possible, and any disturbance has some kind of resistance from the motor prospective. The higher pid rates the more resistance we have. I understand that vesc has the duty cycle mode but that's not the same as speed mode. 

First question: Why vesc implement speed mode in such way and is it some kind of tricky speed control mode in prospect of "classic" speed mode, or the Odrive and china guys implement it wrong?

Second question: Is it hard to implement mode that I've described above?

Third question: Could some one explain with more details why there is a difference in speed mode from different producers?

My case scenario is pretty simple, I want to build the ugv with diff drive steering, and want to eliminate the case when ugv stops in the middle of uphill/downhill and start to go down/up freely. I'm thinking about using duty cycle mode + additional level of autopilot  control for speed mode, but not sure that this is the right way to implement such kind of functionality. I'll also use trampa vesc + spi encoder. Thanks a lot for the answers!