I received the Pentax Sling Bag as a present and was pleasantly surprised with the quality of it. The material used is very nice, and water repellent to some degree (I made a 2 minute run to the car in light rain and everything inside was dry). Padding is very generous, nothing to complain about here. The ability to swing it around to access the camera/lenses is good, although you have to be really careful not to drop things. I tend to swing the bag to the front and sit or kneel so that I can rest the back of the bag on my legs. Compartments are very well laid out. Top compartment is half round and serves well as accessory storage. I usually keep the battery charger and various cables in there. The center compartment has a flap with a double zipper around it. This is where you camera goes. I usually keep the K-x with a medium zoom attached and there is room for a 50mm and another short lens (55mm or 28mm). So you can fit one medium lens (such as kit lens or even the 50-200/50-300 plus two short lenses. The flap itself also has storage both on the outside and inside. Inside there are two pockets which are useful for memory cards or even filters. The outside is a zippered pouch (about 1" thick) which is great for more batteries or other flat accessories. Then there is the bottom compartment which has two dividers, allowing you to store three medium lenses, or one longer one and one medium one if you remove one of the dividers. So to recap, you can fit all your accessories, your camera, and up to 6 lenses (For example your Limited prime lineup) in one very convenient sling bag.
Does anyone with either the Pentax sling bag or the A200 know if I could carry the K100D, 50-200, 70-300, smaller of Pentax flashes (can't remember the number right now), spare batteries, filters, screen viewer (Hoodpro or something, small loupe for viewing on the screen), etc? Could I fit another lens, maybe the 18-55, too? I pretty much find myself carrying the kit and 70-300 right now, but sometimes want the others.
The debate between the Pentax sling bag and the Lowepro Slingshot 200 has indeed been addressed more than once and if you are considering either of these two bags I encourage you to look around the forum to read the thoughts and opinions of others, do some price researching at any number of online stores and carefully consider what you expect from a small sling style camera bag.