I wouldn't drop the Destroyer to replace it with two flippier molds (beast and orc). Plus the Beast and the Orc would kinda overlap with your SL and sidewinder. Keep the destroyer, don't add the beast and orc, and maybe look into an ESP Flash to replace the SL. The SL was a decent disc for me, but it was awful in the wind and glided no where near the level of the Pro Starfire. The problem with the Pro Starfire is that it becomes squirrel city after a month or two. The Flash is faster, just as easy to throw, and glides like a champ. I know I brought up the Flash out of no where, but it's the disc that made me drop my SLs and Beasts.
You definately are missing a control driver, and a Gazelle or Cyclone seem to be favorites of this board. But you also seem to like less stable drivers, which is what I lean towards as well. If you're not liking Gazelles, Cyclones or Teebirds, check out a Z XL. It hold any line I put it on.
You'll probably really like the FLX Buzzz after getting used to it. I'm not a fan of the stingray, and you'll probably find the FLX Buzzz to be a better all around disc that can hold an anny as well as straight shots and hyzers, even when it's windy. I don't know what you use your cobra for, but I'd suggest sticking to one midrange mold if your going for a minimalistic apporach, so I'd dump it as well. I can understand keeping those "comfort" discs in the bag as well, but if you force yourself to use one mid mold, it'll make you so much better on those approaches. When I am playing a heavily wooded course however, I load up on mids.
I'm guessing from your putters that you are an ultimate player as well. Lots of ultimate guys carry putt'rs and rattlers. I've never been a fan of them, and eventually I see those ultimate guys move away from lid type discs toward more popular putter molds. Whatever works for you though.