I built up a bike to suit what is 95% of my local riding terrain – so I opted for a lightweight 100mm hardtail. I’ve used a 6″ FS on the same trails for years and I can honestly say that it’s a joy to be rid of the heavy, sloppy-arsed beast.
Gravity runs are where I excel but I’m weak on the climbs so, to a degree, I went for the current choice because I wanted help going upwards. But the main deciding factor was the honing of my riding on a rigid hybrid on and off road for the last seven odd years. I liked the riding postion and the the weight so wanted something with similar contact points and a similar weight but with fatter tyres and front suspension. So that’s where I ended up.
I know someone who has numerous bikes, most of which are very lightweight. It never made sense until he explained his need to be first to the top. He was never that good going down because he used to bottle it too often. The bikes afforded him the excuse for being slow on descents or, on a few occasions, a total refusal to even drop into a bomb hole. Not mocking, just seems a bit weird to not admit you don’t want to do something instead of finding excuses. I rode a few of those bikes and hammered them – none broke.