Target swaps should be fairly simple, more energy = higher bleed uptime when you're not confined to one target. For AoE, the energy refund helps justify the use of Rip and Ferocious Bite when their DPE is otherwise pretty dismal (at least with many targets). SotF has increased value on multiple targets where FoN's value stays exactly the same.
I suppose DoC has become second nature for me after using it for so long. But even looking at it objectively as possible, FoN causes bursts of high APM and significant proc management layered directly on top of the normal rotation. DoC isn't like this at all, because HT is on the GCD the decision making required is much slower pace and doesn't significantly increase the APM of the rotation.