AW brand 17500s will drive an EO-9 brighter than any CR123s on the market through the majority of the discharge. To back up my claim... do the following:
first have a look here:
https://www.candlepowerforums.com/threads/67078
The EO-9 draws 2 amps, so look at 2 amp discharge graphs of major brand high quality cells....
We see that for the most part, CR123s start off around 2.3-2.4V, some holding steady then around that voltage for about the first 15-25 minutes,, then spending the next 10-15 or so minutes of the discharge falling to around 2.0V, after which point they fall off the map (which would appear as very dim output, you would probably chuck the cells when they dropped a little ways below 2V per cell into the load)...
So a fresh set of really good cells will give you about 7.2Vbatt as the best possible output, diminishing over the course of the run to about 6V before falling off the map.
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Now look here....
https://www.candlepowerforums.com/threads/117117
scroll down to the AW 17500 1100mAH cells.
We see that these cells start off at about 3.9V into a 2A load, and are down to about 3.3V at the 30 minute mark.
So 2 of these cells would start off around 7.8V and diminish to around 6.6V before needing to be recharged. With a useful runtime of almost exactly 30 minutes here.
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If you were to overlay a discharge comparison of the 2x17500 to a 3xCR123 on a graph, with voltage vertical and time horizontal, the AW 17500s would have a higher voltage at any point through the useful discharge of the cells.