Trying to setup a Middleburn duo, front mech and shifter are designed for triple. Anybody got any tips, should I be aiming for using all 3 shifter positions, or just two clicks?

Two clicks I reckon. Have set up one, was a while ago, non-spanner monkey disclaimer.

2 clicks ... what ratios are you running? Sometimes they can be a pain when there's a big difference in ring sizes. You might find that the '3rd positon' on the shifter will still work / move the chain ... just don't be tempted to use it

A combination of the stop screws and cable tension will see you right.

G

It's a pain, it'll work eventually! Running 27/42.

I get a nice shift and the shift pins just clip the mech, cure that crap shift, also not convinced by the JagWire sheathing, hard to get cables tight, so going to strip it down tomorrow and have another look.

So much time spent fiddling with this setup! Turns out the problem was the jag wire sheathing to weather proof the cables, it wouldn't go around the bottom bracket and allow me to get correct cable tension. Almost finished the bike for summer! Leg feels much better following last weekends fall, so hopefully do a stack of miles tomorrow!