rogue sub60 epic or horn as mainhand
 

I can't parse and my laptop cannot install any parsing softwares, so I want to see if anyone has any data or experience on this.

With epic and horn both available, which one should be mainhand at lvl 50, 53, and 55? Or is the diff so marginal that it doesn't matter? Thanks.

Epic MH for BS. By a large margin

does it apply to 50-52 when your backstab skill is low and doesn't land as much, and no minimum dmg or double backstab?

yes. You can search the other thread for calculations. Even at 46 epic would be better. You'd only be replacing MH epic with tunare or vulak stuff