SnD is our highest damage finishing move.
Of course that depends on the target (or another target) being around for the ~30 seconds of SnD time.

You can look at any finisher as an opportunity cost.
If the mob has 1000 hit points remaining, and your Eviscerate will hit for 4,000-6,000 points, some of that is wasted.
Similarly a Kidney Shot is wasted, both because the mob is dead in the next second and because it is then not available until the cool down.
Slice and Dice is almost universally better because even if the mob dies, you have the buff for the next mob.

In a boxing context, against anything other then a boss, you'll be going through mobs very quickly indeed.
I'd be surprised if you get to five combo points that often, with 3 dps toons a tank and a healer.
Even more so, if your healer can and does dps, and only heals when you need them in that role.

/castsequence reset=target/combat Sinister Strike, Sinister Strike, Slice and Dice, Sinister Strike, Sinister Strike, Sinister Strike, Sinister Strike, Eviscerate

That might do for your general spam dps macro. Not sure if its the best, but it will work.

Combat is probably the best spec to box, unless you're going with an all rogue team.
I cannot imagine maintaining a Mutilate spec with say a tank, healer and two shaman's.
Maintain Hunger for Blood always, 1 point Slice and Dice, 1 point Envenom, 5 point Rupture, 1+ point Envenom (to refresh SnD).
A lot more going on with Mutilate then Combat.