Admittedly GB3SQ is a digital only repeater, but it might be worth mentioning the advantage of using the left audio channel on the input side as well as the output side. We use the right hand channel output as you describe it with a relay of the talkback channel. On the input side, unless you are sending in stereo, often audio channels are just strapped to mono. At GB3SQ the righthand channel is used to send DTMF control signals into the repeater, thus keeping the voice channel separate with no chance of false triggering and avoiding the need for an extra VHF channel. Probably not relevant to analog/digital repeaters but might be worth considering for including in the list of suggested settings.