@Mike I just noticed that I only responded to half your questions, sorry!
“Changing infusion sites must mean you have to move things about a bit ocasionally too” – yep, I change my infusion set every 3 days and tend to wear it on my thighs, bum, stomach or back so there’s plenty of places to choose from.
“I’ve also heard about blocked tubes/infusion site probs stopping the insulin delivery which the pumper in question only spotted when their bgs went through the roof.” – yep,it is a risk. It’s happened to me twice in over 3 years. Both times I saw on my CGM that I was rising really quickly, took insulin via a syringe and changed my infusion set. If you don’t have CGM you’re relying on how you feel to spot the rise, but to be honest to get the most out of the pump you should be testing several times a day so you’d spot it then anyway.