Sir (I dont know your name),
I had the same problem with some of the Excitech systems we dealt with. The resolution may depend on which version of their DSP controller you have. What I call the "old" version, which is the first one I used, would never pay attention to F speeds. I had to set the speeds from within the ZHBUSBCONNECT.exe program, then Re-send the file to the handheld each time I wanted to change the cut speed.
The later version of the handheld paid attention to the F commands, I believe, Once I set the setting you were talking about earlier. I believe I have one of those handhelds in storage, as well. If need be, I might can dig it up and see what I can figure out.
Why don't you create a Gcode file of cutting a simple rectangle or circles and send a copy of the G-code for me to look at. Also, send a photo of your handheld along with a model number if you have it. Maybe I can help.
Josh Glenn
www.camaster.com www.cncexperts.com