Thanks for the note, @Nca78 . It seems like my systems defaults to an ID of 255, though. I swapped out another Pro Mini and another radio (debugged the Arduino side using the RF24 library), and now I'm seeing more traffic between the Arduino and the RPi, though it seems to fall over at receiving an ID.
Note that I ran the ClearEpromConfig example immediately before pushing the MotionSensor example (no changes, did not define MY_NODE_ID).
Arduino:
0 MCO:BGN:INIT NODE,CP=RNNNA--,VER=2.1.1
4 TSM:INIT
4 TSF:WUR:MS=0
12 TSM:INIT:TSP OK
14 TSM:FPAR
16 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
2025 !TSM:FPAR:NO REPLY
2027 TSM:FPAR
2029 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
2037 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
2043 TSF:MSG:FPAR OK,ID=0,D=1
4038 TSM:FPAR:OK
4038 TSM:ID
4040 TSM:ID:REQ
4044 TSF:MSG:SEND,255-255-0-0,s=255,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
6051 TSM:ID
6051 TSM:ID:REQ
6055 TSF:MSG:SEND,255-255-0-0,s=255,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
8065 TSM:ID
8065 TSM:ID:REQ
8069 TSF:MSG:SEND,255-255-0-0,s=255,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
10076 TSM:ID
10076 TSM:ID:REQ
10080 TSF:MSG:SEND,255-255-0-0,s=255,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
12089 !TSM:ID:FAIL
12091 TSM:FAIL:CNT=1
12093 TSM:FAIL:PDT
22097 TSM:FAIL:RE-INIT
22099 TSM:INIT
22106 TSM:INIT:TSP OK
22110 TSM:FPAR
22112 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
24121 !TSM:FPAR:NO REPLY
24123 TSM:FPAR
24125 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
26134 !TSM:FPAR:NO REPLY
26136 TSM:FPAR
26138 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
28147 !TSM:FPAR:NO REPLY
28149 TSM:FPAR
28151 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
30162 !TSM:FPAR:FAIL
30164 TSM:FAIL:CNT=2
30167 TSM:FAIL:PDT
40171 TSM:FAIL:RE-INIT
40173 TSM:INIT
40179 TSM:INIT:TSP OK
40183 TSM:FPAR
40185 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
42196 !TSM:FPAR:NO REPLY
42199 TSM:FPAR
42201 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
42209 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
42215 TSF:MSG:FPAR OK,ID=0,D=1
44210 TSM:FPAR:OK
44212 TSM:ID
44212 TSM:ID:REQ
44216 TSF:MSG:SEND,255-255-0-0,s=255,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
RPi:
pi@rpi:~/projects/RF24/rf24libs/RF24/examples_linux $ sudo mysgw -d
mysgw: Starting gateway...
mysgw: Protocol version - 2.1.1
mysgw: MCO:BGN:INIT GW,CP=RNNG---,VER=2.1.1
mysgw: TSF:LRT:OK
mysgw: TSM:INIT
mysgw: TSF:WUR:MS=0
mysgw: TSM:INIT:TSP OK
mysgw: TSM:INIT:GW MODE
mysgw: TSM:READY:ID=0,PAR=0,DIS=0
mysgw: MCO:REG:NOT NEEDED
mysgw: Listening for connections on 0.0.0.0:5003
mysgw: MCO:BGN:STP
mysgw: MCO:BGN:INIT OK,TSP=1
mysgw: New connection from 192.168.11.31
mysgw: Client 0 connected
mysgw: Client 0: 0;0;3;0;2;
mysgw: Client 0: 0;0;3;0;18;PING
mysgw: Client 0: 0;0;3;0;2;Get Version
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:PNG:SEND,TO=0
mysgw: TSF:CKU:OK
mysgw: TSF:MSG:GWL OK
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:CKU:OK,FCTRL
mysgw: TSF:MSG:GWL OK
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysgw: TSF:MSG:READ,255-255-0,s=255,c=3,t=3,pt=0,l=0,sg=0:
mysgw: Client 0: 255;255;3;0;4;1
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=4,pt=0,l=1,sg=0,ft=0,st=OK:1
mysgw: Client 0: 0;0;3;0;18;PING
mysgw: TSF:MSG:READ,255-255-0,s=255,c=3,t=3,pt=0,l=0,sg=0:
mysgw: Client 0: 255;255;3;0;4;1
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=4,pt=0,l=1,sg=0,ft=0,st=OK:1
mysgw: Client 0: 0;0;3;0;18;PING
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:PNG:SEND,TO=0
mysgw: TSF:CKU:OK
mysgw: TSF:MSG:GWL OK
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:CKU:OK,FCTRL
mysgw: TSF:MSG:GWL OK
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:CKU:OK,FCTRL
mysgw: TSF:MSG:GWL OK
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:CKU:OK,FCTRL
mysgw: TSF:MSG:GWL OK
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysgw: Client 0: 0;0;3;0;18;PING
mysgw: Client 0: 0;0;3;0;18;PING
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:PNG:SEND,TO=0
mysgw: TSF:CKU:OK
mysgw: TSF:MSG:GWL OK
mysgw: TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysgw: TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysgw: TSF:MSG:BC
mysgw: TSF:MSG:FPAR REQ,ID=255
mysgw: TSF:CKU:OK,FCTRL
mysgw: TSF:MSG:GWL OK
Am I missing a step? I am running "sudo mysgw -d" on the RPI, followed by "sudo service domocoticz.sh restart", then pushing the MotionSensor example to my Pro Mini.
Thanks again for everyone's help!