Like many, I don't carry anything apart from my test meter when out and about on the basis that I am rarely more than an hour or so from home and although it would often be inconvenient, could always get "back to base" before anything dramatic happened.
Saying that, the other week, I made a trip to London on the train - out for the day, 200 miles from home doing some work. Checked that there was enough power in the pump battery then packed a vial of insulin, reservoir and an infusion set along with a supply of Jelly Babies (5g of fast acting carbs each one and my hypo treatment of choice since my DAFNE course) and my test meter. As it happened, no worries, quite an uneventful day as far as diabetes was concerned. However - when I got home, it dawned on me that I had not taken the plastic spring loaded doo-dah which is used to fire in the cannula. Ooooooo! No doubt I would have managed without it if I needed to change my infusion set - maybe - or at least had an attempt but I think that carrying one of those would be something to think about.
Alan