I've been a first-day adopter since Lion but I'm not so sure I will upgrade this time as Sierra will not run on my 'pro 4.1' (flashed to 5.1). Yeh I know I can 'hack' to maybe get Sierra installed but I can't justify the time/hassle to do so unless it's risk free. Is it risk free, I don't know enough to be able to decide. So that leaves me with running Sierra on my rMBP and El Capitan in the 'pro' which I am less that excited about. Anyone else with this same dilemma?