I did some more testing just now. This test was to figure out whether it's better to use BS for death runes vs oblit. I didn't even have to dps for 2 mins to find out the answer for this.
These are the two specs I used and yes I know "Combat dummy is stupid testing" but when comparing two specs with each other that both involve mostly the same talents I think it's safe to say it's fine to test it this way.
Both specs have no glyphs affecting any abilities.
Weapons used were 2x
[Razorscale Talon] main hand FC offhand RI (RI was up 100% of the time)
[Sigil of Awareness] was used.
I never used unbreakable armor in any of the tests.
Howling blast wasn't ever used during this test.
HoW was up 100% of the time and Arcane Torrent was used every time I could use it. Deathchill was used primarily on FS. Sometimes I'd get unlucky and I'd get back to back KM procs so it would get used on IT instead.
I had to use the ebon knight's training dummy due to the fact that too many dks were using ebon plague on the boss dummy.
Spec Used:
http://talent.mmo-champion.com/?deat...version=10026#
Test 1
Using Oblit for death runes
IT -> PS -> oblit -> BSx2 -> RP dump
oblit x3 -> RP dump

yes some dumbass decided to come to my dummy out of all the ones in there that were empty and start attacking it and putting up ebon plague. I had to stop the test early

(only about 300k short but it looks pretty clear which one wins)
Test 2
Using the same spec I decided to try and use BS for Death runes to see how it goes. Here are the results.
IT -> PS -> Oblit -> BS x2 -> RP dump
Oblitx2 -> BS x 2 -> RP dump
I was wearing 2pc t8 and 2pc t7 for this test. I get the feeling that even if I had lost the 2pc t7 bonus oblit would still be on top due to the large amount of crit it gains from the frost tree too.
I know somebody did some math with BS being more damage than oblit however I don't think they factored in the crit bonus that oblit gains compared to BS. Hopefully this can help out if needed. If you need anymore info let me know.
edit: Changed original post to now show only using 1 spec and using BS for the 2 death runes instead of oblit.