I use it on both mac and windows (windows when doing extender development)
On the windows version, if I upload an extended version of a remote to the remote, do some stuff, deactivate the extender and do a 981 reset and then download the remote, the raw data tab still says that I have the extender in even though the signature says it does not. (and the bytes that tell what the extender version are FF FF so the remote is not telling RMIR that it's got the extender)
the extender has a bunch of protocols installed into it for the special devices. I used to see the protocols in the table. They're not there anymore, I don't know if you are hiding them by design or if this is a bug. The devices for these special protocols still show up in the devices tab.
when I build debug versions of my extenders I sometimes put in pre-defined keys in the special protocols tabs so that I can do debugging. In this example I have pre-defined keys for 10-sec and 20-sec pause and the debug version of the extender blinks the LED at the start and end. I use this to ensure that the timing is "roughly" right. when I install the extender file on the windows version they show up. When I install them running on mac they don't.
Windows:
Mac:
these run the same version of RMIR and were done by doing a 981 reset on the remote then loading the same extender hex file.