My current wheelset is about 1900 grams (Mavic XM819s on Hope Pro 2s with DT Comp spokes, brass nipples)
My planned new build should get close to 1600g depending on a few decisions I haven't made yet. I'm currently planning on going with WTB KOMs (probably i23, maybe i25), either DT Revolution or Sapim Laser spokes, almost definitely staying with brass nipples. I'm debating whether to re-use the current Pro 2 hubs or get something new (probably Pro 4s).
It's pretty much down to this: do I buy the i23 KOMs, re-use the hubs and have them built locally (or DIY it) or do I get i25 KOMs on Pro4s from Chain Reaction (they don't offer the i23s for custom builds for some reason) and keep the current set around? The second option is only slightly more expensive, so that's the one I'm leaning towards. I just have to convince myself that the extra 20 grams per rim for the i25s isn't a big deal and that the extra width will be fine...
I'm tubeless already, I just carry a tube as a "just in case". For tires, I'm running 26x2.25 Michelin Wild Grip'R2 Advanced, so not too heavy at a spec-ed 570 grams per tire. Definitely not bad weight-wise for how well they grip (and they roll nicely too).
For the rest of the bike, if I wanted to start throwing $$$ at it, I could start replacing the XT drivetrain with lighter bits. But it works very well as-is, so... And the wide range / close spacing combo with the current 3x9 makes the bike a great do-everything setup. Cassette is an 11-32, I've got 26/36/48 up front (soon to be 24/36/48). Low enough gears for singletrack, fast enough gears for smooth stuff going downhill and close spacing for sprinting or keeping a comfortable cadence with some weight on the rack.