A NW2 hairline is not a problem at all for those in their 30s and 40s because at that age you just need style, physique, money to make up for it. You don't even need all of those things, just one will do. I have a about NW1.5/2 at 36 years old, and it has not affected me one bit.
The problem with the thinning crown is it pretty much indicates game over. It is a guarantee that there will be a point in your life where you will be an obvious balding man. I have a thinning crown that is not noticeable to anyone when dry, but I already know I'm bald in 5-10 years despite dutasteride, and I will not be able to have a transplant to get an acceptable result.