A few reasons. * I can read the code. It's not very complex. * There are minimal moving parts. * I can suspend the pump or disconnect at anytime. * It's changi

A few reasons. * I can read the code. It's not very complex. * There are minimal moving parts. * I can suspend the pump or disconnect at anytime. * It's changing my basal rates (minor adjustments) not randomly bolusing large amounts. This isn't an "overdose" type situation. * I'm fully in control of my facilities. I'm not a child or an older person - each of which are more likely to have hypos. * I have never had a debilitating hypo in 20 years, I'm not planning on having one now. * The system was designed by diabetics, for diabetics. The closed systems that will come out like Medtronics will be VERY conservative. So much so as to be of questionable use to folks who want an A1C <6% Because of all these reasons, along with 15+ years of pumping alone and doing the calculations in my head (and getting them wrong) I choose to trust these systems.