I'm actually to the point where I think too much import is put in the cells we are using. Here's an interesting (or at least I think so) comparison.
This is part of a graph of a constant 3A discharge. Its also using watt-hours instead of amp-hours. The Trustfire (flame - bought from Manafont) puts out 88% of the power of the Panasonic based 3100 when going down to 3.0v. At 3.25 only the Sanyo is out ahead of the pack.
From what I've tested the NANJG 8x7135 driver ACTUALLY cut out above 3V. I'm not sure if its the resistance of the host or what, but I can't get LiFePO4 cells to run on this driver on high at all. These cells have VERY little voltage sag so I know its certainly above 3.0v battery voltage.
A little bit of a tangent, but I just have observed that specifically with the 8x7135 drivers you are wasting a lot of capacity.
Now in the dressed up direct drive lights like the 980L, I think these higher capacity/lower voltage cells are a better choice.