Great post Oli, its a nice timely reminder to us all.
In-fact, the only time I have used FESTO press-on connectors "on the suction side" was for my Turbine powered EC135 with the two-stage JetCat SPM5-HM.
Due to the internal heat inside the cabin the Polyurethane became way too soft for my liking. I then modified the entire fuel system to 4mm Brass/Aluminum (from K&S), and Teflon.
