Someone Mathhammer for me real quick!

Im horrible at math...so dont poke fun.

I was wondering...playing against monstrous creatures with Dark Reapers....which shots I should use..

assuming I have cast guide and doom on respective targets, shooting at something T6 and above... Is it better to use the S5 double shot, or the S8 single shot?

ignoring hit and saves and damage (not sure both 1 right?)

without doom vs t6:
After hitting with 1 s8 shot: 0.66 average
After hitting with 2 s5 shot: 0.66 average

With doom:
After hitting with 1 s8 shot: 0.88 average
After hitting with 2 s5 shot: 1.11 average

So with doom (reroll all failed to wound right?) the lower strength is slightly better.

Assuming a 3+ save and/or 5++ with Guide and Doom the S5 does 1.32 damage on average against T6, whereas the S8 does 1.58

T6 - 1.32 (1.58)
T7 - 1.32 (1.58)
T8 - 1.32 (1.33)
T9 - 1.32 (0.99)
T10 - 0.72 (0.99)

So basically, the S5 shots are better against T9 but worse or equal against anything else (unless you get to T16+)

thank you much! I was playing a game earlier, and had a unit of 5 dark reapers trying to take down two demon princes. Luckily he made a few mistakes (chasing after chaff) and I was able to down his last demon prince right in front of my Dark Reapers!

So in conclusion....you want to use two shots at T5 and lower, or T9