Thanks, Brian.
Yes the emonTx 6pin header is connected to the Pi’s GPIO as per the usual “serial-direct” which I believe is documented somewhere in the wiki/site(s), the only real difference being I also connect the emonTx header’s “reset” pin to the Pi’s GPIO18 (pin12) so I can upload sketches to it much the same way we can to the RFM2Pi’s.
I choose to use just the “even” pins 4(5v), 6(gnd), 8(tx), 10(rx) and 12 (GPIO18 “reset”) so a 1x5 way connector could plug on to the Pi’s GPIO alongside the “odd” pins used for the pulse counters as described above.