I still think that chasing down grammes is a fool’s errand. It’s easy to end up spending several grand on removing a pound or so in weight and having to deal with the inevitable compromises involved – i.e. durability or in the case of bar width, bike fit and handling. I’ve been there and ended up with a bike that was light, but too delicate and compromised for the riding it was originally designed for.
That said, I’ve two bikes – one carbon, the other aluminium, both with circa 140mm rear travel and 150mm Pikes. The alu bike is a 29er and is a good four pounds heavier, but that’s the difference between a full or empty Camelbak. I try not to think about the weight on the trails.