I have a large entertainment center that needs to be mounted to 5/8" drywall with metal studs. The entertainment center weighs about 180lbs by itself. In addition, I'll have a tv flush mounted, pictures, books, and surround speakers on/in the entertainment center. I plan on using strap toggles for all of the anchor points. There are 6 brackets holding the entertainment center to the wall, with two anchor points (screws) holding each bracket in. My question is; if I use toggle straps for each anchor point (12 in total), and each toggle strap is rated to hold up to 70lbs; will that be enough to hold everything? In other words, will the weight be dispersed across all the toggle straps, so that each is holding well less than 70lbs? ...Also, should I be concerned about the structural integrity of the wall? There won't be much weight coming out from the wall; no swivel mount, just shelves that are about 12 inches deep; so we're talking mostly shear force.
So this entertainment center is actually all hanging from the wall, not sitting on the floor and anchored to the wall to protect from tip-over? If so, given the weight (perhaps 250 lbs. but the time you are done with everything), I would NOT rely on drywall anchors of any type but would much prefer to anchor directly into the metal studs. Getting into metal studs is not as easy as wood studs (e.g., 2x4s) but it can be done and is quite secure. One method is to use some wood (either a rectangle of plywood or two strips of lumber) and secure that wood to multiple studs and then you can use screws to hang pretty much anything on the wood. That is routine for telephone/network equipment (not because of weight but in order to have a large area to connect things to, many of which are too narrow to necessarily hit any studs for mounting) and will work quite well here too. As far as "looks", if some of the wood will be visible, paint or stain it to match the entertainment center and nobody will notice.
If the anchoring of the entertainment center is only to prevent tipping over, a few ordinary anchors will do just fine, even if they can't hold the full weight (because they don't need to).