Multiple anchors and weight dispersion
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).