I personally think Ignitors suck asss in some ways. I blew/tore the sidewall on a relatively girly rock garden that I have done many times....weaksauce. The sidewalls are paper thin. For XC riding I think an ok front tire as they have a decent knob pattern for turns but I would not run as a rear myself.
As far as tire weights, there has been a TON of variability reported for the Ignitors. Weights as high as you are mentioning and I have seen many documented reports of 580 gram range. Mine weighed in at 620 grams a piece.
I will not buy them again.
For SoCal rocky riding I still think the tire to beat is the Exiwolf. On my so-called "All Mountain Bike" I now run Exis front and rear. Fyi - newer Kevlar Exiwolfs are only 770 grams a piece or so (both of mine are about this weight) so a great weight for the tire. Not the greatest at cornering but good enough....and robust through rock gardens and can handle pretty low psi very well.
The other tire to beat (as a front tire anyway) is the new Panaracer 2.35 Rampage. I will probably try it as a front tire next round. Reported/documented weights right at or slightly under 800 grams which is very impressive as far as I am concerned.
Here is a pic of a 2.35 Rampage (right side) next to a 2.3 Exiwolf (left).