It's no way you are getting 1000 (real) lumens from a standard xm-l p60, it must be overdriven pretty hard to actually reach 1000 lumens. The extra heat from the overdrive will make it hard to actually reach 1000 real lumens. I think the quad xp-g modules might be the brightest.
My torchlab triple xp-g R4 (rated at 1000 lumens) is brighter than any of my "1000 lumens" el-cheapo xxx-fire xm-l modules. And it only got 3 neutral xp-g's.