average hit #s from 100+ hits on a training dummy. It is lvl 102 so its armor is a bit lower than a raid boss, so swipe/mangle damage are probably a few % higher than they should be, but it doesn't really change anything. Of course that's a highly simplified set of math too, so don't take the #s too seriously. It's pretty much just to show that GG (DPS)>SotF>GG (Rage) for DPS, any real comparison of DPS numbers between the specs should be left to sims, which can be made much more precise.
Guides aren't also necessarily wrong to write off SotF. It's a newb friendly option for single-traget that's pretty well balanced for that spot, but it becomes trash the moment an extra target wanders in. If it were made more usable in AoE situations (by making mangle do ~20% splash damage or something along those lines), then it could be called a good newb-friendly general-purpose talent, right now it's almost always bad.
No beta access, so I can't comment on any specifics for artifact traits.