In case anyone is following this progress, I have a bit of an update:
I've been testing HG for a few months now. It sits behind a FilterLinc so it doesn't actually control anything, but it gives me the opportunity to tinker with the scripting to verify I can get my most complicated feature working (motion controlled entry lights with a twist). I am by no means a C# programmer, so it took some time to get the code working, but I was able to work out the final kinks a couple days ago.
Sweet! Well, sorta. The code works correctly but not quite as well as AHP in terms of speed. The issue is centered around the use of an override switch (ToggleLinc) to force the lights on/off even if the motion sensor has been tripped. My current setup (ToggleLinc->PLC->CM15A->AHP SDK->AHK script->AHP SDK->CM15A->PLC->WS13A) consistently takes just under 2 seconds to turn on/off the light when the switch is triggered.
The new setup is the same except for the use of AHP and the AHK script. Instead, I use a Raspberry Pi based HomeGenie to receive the command and a C# script to process the command and send out the response. In the case of the new setup, it takes between 2-4 seconds. If I had to guess, the difference is that AHP is event driven (processing the command as soon as it comes in) whereas HG is polling at some interval for state changes. That's the only reason I can think of for a random response time.
The WAF for a <2s light was low but acceptable considering that the rest of the setup worked perfectly with AHP (after their servers returned). The WAF for a 4 second light is exactly zero! So, unless the author of HG can come up with a solution to improve the response I'll likely have to consider a different option.
I am currently looking at Domoticz as that option. It has all of the features of HG plus a lot more. The main reason I picked HG initially was that it worked with Windows so I could look at it before buying the Raspi and had a prebuilt SD card image. Domoticz did not work when I tried it initially, but it has a SD card image now too that works out of the box.