They're two different types of bumper. Caze Thin is very thin with minimal drop protection, then again you shouldn't be getting a bumper if you're looking for drop protection. The Caze Thin also has no tactile buttons over the volume and sleep/wake button while the Linear Ex Slim does. This can be a big thing to certain people like myself. Some people prefer it being open while other prefer there be some cover over the buttons. The Linear Ex Slim is plastic with a metallic finish over it. Or you could wait for them to release their other 10 colors. You can mix and match if you wanted too. I believe they are releasing 14 different colors. The Linear Ex also has a slighty bigger lay on table both on the front and back. The Caze Thin is thinner so if minimal bulk is what you're looking for you should really check out the thread people people posting up pictures of it.
It's all on personal decision. There is a thread on the Caze Thin that you should check out.
As far as the Linear Ex goes, ill have a review up today/tomorrow.