I did it! It helps to have the drivers installed properly. I downloaded the 4.8.0 drivers package and installed it, then changed my phone to "PC mode" and it found 4 devices and installed drivers for three of them, strangely, failing on the "MTP USB Device". I assume my computer suddenly located these drivers thanks to the recent install of 4.8.0.
I don't know what "Motorola Driver Installer.exe" is or does, but it appears to be useless.
Anyway, the script worked but I don't know yet if it helped my speed. If it is noticeable... I'll notice it.
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slightly off topic now - what is "MTP USB Device"? Just curious what failed to install.
Also - I switched to USB debugging and the other devices disappeared (which is expected) and "A956" popped up. I was never able to get A956 to install properly, but now 4 other devices are installing including ADB interface - which I already had.
I switched to "charge only" with USB Debugging still on, and a different "Mot Composite ADB interface" showed up. It, too, installed properly.
Finally, I switched to mass storage with USB Debugging still on. The PC recognized the phone as a USB storage device, and this time instead of an ADB Interface Device type, I have "Android Phone" - Android ADB Interface. ADB sees my device, so we're all good.
Lastly, turning off USB Debugging makes the phone show up only under DVD Drives as "Motorola A956 USB Device"... it also causes a Verizon tab to open in Firefox.... mighty annoying.
All along I had Easy Tether running, which is a separate driver altogether, and my PC recognized it no matter what mode I was in, as "Easy Tether Network Adapter" and was available to connect.
I am happy! Looks like my D2G and my PC are finally talking to eachother!