I will answer myself after some testing done today:
How can I change network id for gateway (mysgw)?
It is possible to change MY_RFM69_NETWORKID for mysgw by exporting CPPFLAGS variable with the option set before running ./configure:
example:
export CPPFLAGS='-DMY_RFM69_NETWORKID="101"'
./configure --my-gateway=serial --my-transport=rfm69 --my-rfm69-frequency=868 --my-is-rfm69hw --my-serial-is-pty --my-serial-port=/dev/ttyUSB-MysGW --my-serial-groupname=dialout
make
Is it possible to create another RFM69 network on new hardware, just for the test, while my current RFM69 network keeps running on current gateway/controller?
As soon as I started another RFM69 gateway (mysgw) on new hw, even with different network id (101), most of the sensors connected to my other (production) gateway running on old hw with default network id (100) stopped communicating... so it seems it is not possible to run multiple RFM69 gateways in the same range (on the same freq).
I liked domoticz (was very easy to set up and use). Together with dzVents scripting wasn't that difficult either. But I also had some problem with it lately, so I was actually thinking about switching to openhab (2).
