Please help my demo play!

[Guest Adjoint]

I'm playing demo specced into wrathguard, archimondes darkness, glyph of dark soul and demonbolt. I have killed kargath twice, once on normal and once on heroic and although I didn't need to move much in either kill I am seeing huge differences in my logs.
 

First Kill (normal mode)
https://www.warcraftlogs.com/reports/6gb79dpPTr1tDKB4#fight=5&type=damage-done&source=64

My first kill (normal mode) actually ranked #1 in the world at the time. My opener was prepot+precast soul fire, wrathstorm+HoG, corruption, terrorguard, dark soul+HoG, meta, demonboltx2 and then doom. I use doom after my demonbolts as I'm terrified of not having the fury for the second demonbolt. I bursted almost 60k in this kill. My rotation throughout the fight seems fine to me, but please let me know if you see any problems, however minor they are.

Second Kill (heroic mode)
https://www.warcraftlogs.com/reports/QcdgyX6GqWHMkf4j#fight=2&type=damage-done&source=21

I'm not expecting my dps over this whole fight to be as high as the normal mode kill since this fight goes much longer. But there is a ridiculous difference in burst here. The reason for this could be because someone pulled early and I did not have time to precast soul fire. My opener was the same as my normal mode kill with the exception of not having a precast soul fire, except when I got into meta I did my 2 demonbolts and did not have fury for doom (thank fuck I didn't start with doom in meta, would have had no fury for the second demonbolt otherwise). I applied doom when meta came back off cooldown, about 15 seconds into the fight. It's worth noting that in this fight I had the 655 staff from tectus, while in the normal mode fight I had a 640 staff from CM daily.

But surely doom and the lack of precasted soul fire is not responsible for such a large disparity in burst dps. I noticed that in my normal mode kill I had an unusually high amount of demonbolt multistrikes. Did the RNG gods just bless me in my normal mode kill? Did I make mistakes in either kill? Any advice/comments on these two kills are appreciated. I do not yet need advice on my other boss kills, I made very obvious mistakes on those that I can fix myself. But these two kargath kills are showing very different results and I'm not sure why.

It's not even the opener that has lower dps in my heroic kill, it's every demonbolt burn. I'm starting to think that multistrike and crit RNG plays a huge part in demonology dps as such a high amount of our damage comes from a spell we cast a low amount of times.

Armory link: http://us.battle.net/wow/en/character/frostmourne/Adjoint/simple
It has not updated yet, the helm was replaced with a 640 epic with socket from CM daily and the weapon was replaced with 655 tectus staff with a socket. I don't think gear is relevant to my confusions here anyway.

Edited December 4, 2014 by Adjoint