Here’s my 2016 Crosstrail disc build @ 23 pounds:
Mods: Salsa cro-moto cromoly fork (weighs 2.2lbs), 25 mm WTB wheels, WTB resolutes tubeless, Stans sealant, Gorilla tape in the wheels, Renthal carbon fat bar, Redshift 100 mm 6 degree stem, XT brakes, Ai2 rotors, Ixf crank, Generic Amazon 38t oval chainring, Sunrace 11-40 cassette, Ec 90 carbon seat-post, Toseek carbon saddle, Esi grips, Origin8 bar ends, Nashbar soho pedals
Total cost of upgrades: approximately $1033
Posting for others wanting to do a light-weight gravel build. With a carbon fork I could hit 22lbs but the Salsa cro-moly fork has taken blue/black trails and multiple crashes without issue so I might just leave this as is. Climbs way, way faster and turns much better than stock. I hit and sustained 26 mph on a flat straight stretch on my last ride, almost identical to what I reach on my 20lb road bike on the same stretch.
Possibly I'll do a GRX or AdventX drivetrain in the future but the stock Altus derailleur is already smooth.