My 2 cents.
I would implement a discrete start/stop signal or via comms to the drive and not rely strictly on the 4-20ma signal. While I do recognize the "sleep/wake" mode will deal with the lack of resolution effecting the low signal level (4mA) if you get a surge on the analog signal you could get a jump in the drive. If the discrete input is off then it won't matter what the analog signal is at, the drive won't start. Having said that I'm not a "drives" expert so I don't know what standard practice is but I use drives a lot in demo displays and if I had to deploy one in an application I would feel much more comfortable having a digital signal control the start/stop with the analog controlling the speed.
Again, just my two cents.