I took cgsprings' recommendation from a different post and I ordered the large sturdy (for bigger bags) and a small (to place inside). I take the small one out when I want to change bags....it takes a few seconds. Sooo easy. My only advice is to measure your wallet....or whatever you plan on putting in the center of the chameleon when it is inside your bag. I have a long wallet and it doesn't fit well inside the centre area....which annoys me.
How well does this work with slouchier bags? Is it stiff like the Purseket?
It's not stiff at all unless you get the large extra sturdy. That one has two cardboard inserts on either end to keep it standing upright. Other than that, it's a very flexible nylon fabric.