Guessing that it is correct. BUT I do not have a CM15 USB device here. (have the rest of the stuff that utilize RS-232)
It is being tested in UK with an RPi3-Jessie Lite user there. It was compiled from your github over there.
It works 100% with Wheezy, Ubuntu 14.04, Debian 8 just fine. It is not always 100% with Jessie, Ubuntu 16.04 or Debian 9.
Figured as you are an automation grandfather and involved in Mochad development then standardizing on your build would be best.
Sorry not sure what you mean by 'weigh down'.
It is said that the addition of systemd versus upstart utilizes the CPU more.
This is more evident on the RPi2 running Jessie Lite versus the RPi3 running Jessie Lite.
Personally seen overall utilization higher here on the RPi2.
The ZigBee GPIO has been out for a while but there wasn't much relating to drivers for it. There are now drivers and a plugin for Homeseer.
It looks almost identical to the ZWave dot me GPIO card.
Personally thinking the antenna is bigger and because it sits on the GPIO RPi bus it works better than using a USB port.
Here stacking only a ZWave GPIO card on top of a PiFace RTC shim. Years now. Works great.
Beefed up power supplies along with testing on the Pine64 2Gb machine (power sucker) so bulk purchased PS's.