Don’t the i-Beams have a bit of reputation for breaking?
Couple of other areas you can save weight on items you’ll probably be buying anyway are a KMC X9 SL chain (~250g) and an XT cassette (~260g) -XTR is lighter but much more expensive.
And if you use 6 bolt rotors Alligator rotors are very light and cheap, as are Ashima rotors from Merlin.