Perhaps a Simple DRK Solution

[Chronons]

So your idea, doesn't make a lick of sense. You would do 15% more damage just using Normal+Darkside. With Normal+Darkside+Grit+B4B your taking even more damage with 15% less damage.

The difference is that activating BfB while in Grit is less of an investment than stepping out of Grit. Also, as someone pointed out earlier above the skills are multiplicative meaning if you used BfB in Grit you would still be taking 6.75% less damage than normal. From a dps perspective it is of course not as effective as stance dancing, however 3.2 changes to tanks have made stance dancing a less liberal affair for all tanks. That means the gains from BfB while in Grit are potentially substantial. I love the analogy that FallenWings used of a poor mans Unchained because that is almost exactly what this would function as. Also, great point about BfB effect on emnity generation while in Grit. That could lead to more efficient stance dancing for DRK.