I just changed my 990 to a single rotor. Here are the actual weights...
This is the two calipers. So you save half of that which is 1.13 Kg
This is one stock rotor. 1.38 Kg
If you go with the Galfer rotor you save an additional 0.5 Kg
So total removed unsprung weight is 3Kg or 6.6 lbs
You decide if you think thats worth it.
4x in 2012 Baja 1000 solo on 990R
( Pinkbike, Chainslayer, Klim, Black Dog CW, Gnarly Parts, Fastco, Woody's Wheels, SuperPlush, Dirt Tricks, Renazco, CJ Designs )
I'm Radek from Road To Baja Documentary
2006 KTM 540
, 2008 KTM 530 xcwr, 2010 KTM 990R