In the OP’s situation if the Sham isnt tanking or rooting to help the rogue BS off cooldown, yea just swap in the 12/20 and melee like a boring ranger.

I actually have had the opposite experience. Never make parses mainhanding RB, but consistently just under the NToV/Tuna rogues when I go 12/20 mainhand instead.

Vindi is a relatively low AC raid mob, actually. I generally break 100 dps on him. I'm very skeptical a low delay to max damage bonus is a good idea there vs. backstabs.

AOW and Tunare, maybe. Both of those take like 2/3 of the damage Vindi does, and the unreduced damage from the mainhand does more there.

Generally, I expect to hit about 50 times a minute with Ragebringer mainhand, and thus about ~62 for a 20 delay off hand. With an 11 point damage bonus, that gives an extra ~2dps, which is then lowered by the backstab damage drop.

AOW min hits a huge percent of the time on backstabs, so it might be marginally better there. For anything where you're going to do at least 536 backstab damage per minute above the 120 min cap, I am pretty sure you should outdps with the 15 damage mainhander.

Regardless, the difference is small enough that I'm just going to mainhand the 15 damage weapon and keep that.

Do not use the scimitar. It's too slow.