It stacks with rogue and monk extra range for quarterstaves, so I believe it would stack with keen edge as well. Gonna log on and try.
The other big question if it stacks, is whether or not it's supposed to stack. I'd hate to see it go live stacking, then get nerfed later on after people have had a chance to make builds based on the stacking properties. Turbine? Do you want to chime in here?