I cant speak to the Swing rack or Woo. I do have the Spider & the Adjustable rig which imo is more versatile than the Woo. I had the same issue as you. Wanted to increase capacity. Any raised grid setup will give you more room for butts. I've routinely do 4 butts at once on the rig. I could do more but havent really had the need. I think I could do 6 pretty easily maybe more. You won't be able to use the platesetter with The Rig. Thats where the crossbars and Spider comes into play. The BGE pizza stone fits perfectly in the spider to go indirect. Also CGS has some nice oval shaped stones to use on the crossbars. What I like most about the rig is being able to move it up and down to different levels and the ability to add another raised setup on top of it. This is where ribs come in to play for me which is my favorite cook. I traditionally always used a rib rack but found when it came time to sauce I hated the vertical setup. With The Rig you can easily do 6 racks of spares FLAT. Also with The rig being its own platform you can take it out of the egg while cooking to change the setup, rotate racks (important for ribs) and keep the dome shut so your fire doesnt run away.
Again I haven't used the Swing Rack. It looks interesting but I'm not sure it is as flexible in terms of setup. Seems more just to increase cooking space. Others can probably speak better to it.