I recently purchased this package and so far it is much better than expected and is even cheaper. Although it is missing things I would like, like the float and case which I had to buy separately.
I bought one of those assortment bags with about a million GoPro mounts and straps and headbands and body-harnesses, etc... and they all work fine with my SJ5000 Plus.
But yeah, like others have said, the waterproof cases are not interchangable.