Ive had Purp phenos go from 8 weeks - 14 weeks. Especially bagseed Purps. It can go the distance. You have atleast 4 more weeks on that girl. But if you refuse the advice given and you want to chop now then its up to you. This is what your top should look like when ready. I actually could have let her go 1-2 more weeks to ripen up a bit but I needed the room so I chopped at 9 weeks. 11 would have been mint. Your is much more sativa if its been flowering already for 10+ weeks. Def give it 3-4 more weeks. Feed it lightly for 2 more weeks then flush it and youll be ok.
Your Purps looks like its only been flowering for 5 weeks. I do believe you about the 10+ weeks. Its just gonna take alot longer on this pheno. Its a good thing with those sativa dominant Purps because those phenos get you much much higher than the 8 week Purps. I know. Ive grown it for years. Its been my main stay since day 1. Do whatever you want though. Im telling you though, if you harvest now it will only give you a sweaty forehead, racy high thats from like highschool days. You will not be happy.