Unless you are a serious neat freak or just lookin for another way to spend money those carry bags are extremely unnecessary , especially for detectors on the cheap side.
I have a soft bag that came with my BH Lonestar that works pretty well.
When I travel. I carry all of my gear in a bag like this. I carry extra coils and rods, batteries, first aid kit, digging tools, storage containers, camera and tripod, detector, headphones and whatever else I may need.
Tactical Bag. 3 zippered outside pockets, 3 end pockets with Velcro closure. Adjustable padded shoulder straps for backpack usage, vinyl waterproof bottom. Size: 15in. x 34in. x 12in.