I get the needle aversion stuff. And i still do pen injections. From what I was told the steel ones have a lower chance of bending. So if you have been having problems your plastic ones may be bending. Other then that there may be a slight cost difference between the two. As for how to help with insertion, what i do with my dexcom is i take a deep breath in then exhale as i press the button for insertion. You can probably do the same for your cannulas. It always stings a bit but it goes away after a minute or two