Results in full color picture form as follow:
Death Strike at Nil RP - avg. hit 708
Death Strike at 50 RP - avg. hit 777
Death Strike at 130 RP avg. hit 856
Seeing that 50 RP result and full RP result are not the same, I propose that the tool tip is in error and should read "for every 5 RP" instead.
Quick and dirty, I know. But regular sources seem confused and I'm not entirely sure this isn't a result of bad data from Blizzard and some conjecture in the theorycraft community (wowhead data mines, wowwiki doesn't iirc). I haven't seen a full analysis of this particular bit of info and I feel sorry for the poor sucker who would have to perform such a series of mundane and dull tests. But the above should be good enough for simple discussion.
Comments?
Cheers =)