I have a 6s Plus on iOS 10.3.3 Every now and again....maybe once a year I like to just wipe my phone...setup as new device and start from scratch. I always find that when i start feeling like its sluggish or buggy and I need a new phone, this cures it. Recently I saw a speed test with the 7Plus and 8Plus. I decided to do the same test opening those various Apps in sync with them, and was astonished at how many my phone opened faster than both the 7 and 8. And now worried about updating to iOS11 and slowing my phone down. So my question for those who know...If i factory reset my phone, will it come back with iOS11 or where I left off or what it originally came with?