I actually scored better in Fire Strike leaving boost enabled. I tried both, my max stable overclock without boost and leaving boost enabled. Reason being, boost will occasionally be stable at higher clocks than what I locked my core clock at. Then when it needs to drop down, it will dip for a few seconds. I really don't see a reason to disable boost if you can get your card to boost high enough.
On my 960, my max "stable" overclock is 1560-1565Mhz. I can just set my boost to ~158XMhz and let it drop when it needs to. It mostly hangs around ~1575Mhz and rarely dips to ~1555Mhz.