Brooks Saddle: How to tell when they are worn

I bought an Aged Flyer 6 years ago and may have about 1500 km on it. Has been mostly comfortable, but noticed the last couple of rides some pressure on the twins. My seat has very pronounced seat bone indentations, with the centre spline noticeably higher. I've never tightened the seat, nor the laces and plan on giving it a bit of an adjustment but was wondering if I made a mistake getting the aged leather. I understand that it is thinner and treated which makes me wonder if the leather will lose its shape much quicker than the B17's.