Looking really good- I have to put in my vote to wait longer. 10 days doesn't seem long enough for those buds, my bet is with another 20 days those things will be insanely delicious, frosted over, and on fire with red hairs. There are some great threads on here that have made me realize you are much better off harvesting late than harvesting early.
My Northern Lights are just finishing up at 9.5 wks flowering. Thats supposedly an indica dominant, which have shorter flowering phases than sativas. As good as my girls look, I'm convinced I could let them go 10 days longer without any damage done, only sticky goodness. If you're growing a sativa, you should not be surprised by flowering periods of 12weeks and over. I'm not too educated on the genetics behind Purple Kush, and of course theres always the off chance that you're not actually growing a Purple Kush plant, but unless its straight indica you should be prepared for the long haul.
Once again, great job so far. I just personally believe if you wait longer, you will by no means regret it. However if you cut early, you might find yourself saying "fuckitall, i shoulda waited"
