Ds13 uses Omnipod (just passed one year mark!). He knows his I:C ratio, even though the pump has it programmed. I'm the one who would need to rely on a print-out to verify the info. Like several posted upthread... he estimates his carbs based on what's on his plate, how he feels, and what his day has been like. He's usually on target, though not always perfect. He was dxed at age 11 and was interested in mgmt of dosing/counting from the beginning. So his interest doesn't surprise me and I hope he keeps up the good work through the rest of his teen years.