wall anchors differ wildly. The big corkscrew kind that screws into the drywall, I think would be fine. Then there's many kinds of plastic anchors, some are more "spiney" than others, and I am betting this is what that person used that had the crash, as these i've found can be the weakest type of anchor to use. also have to be careful when drilling the hole, not to make it too large with the plastic spiney kind.
I ended up using toggles, but they weren't in a package so I don't know the weight rating. I think the weak point is the little nut inside the toggle can be thin and bend/warp with too much weight ... with this thought, you should use large toggles (which is kinda annoying to make such a large hole in the wall), or use something that really connects with the wall such as those corkscrews or the things that spread out behind the wall that I linked to in my original question above... Those two (corkscrew & spreaders) I think are better than using toggles that are too small since those could fail pretty easily if they bend...
anyway, like I said, I'm using toggles, but I don't feel confident in them. I may switch to something else, or bigger toggles... otherwise, it's good so far, it's not like we're hanging or jumping on this speaker. haha. :) and i have insurance as there's a mantle directly under the brackets (I used the brackets since I didn't trust the mantle)..
5.1: 4x5B 1x5C 1x10D