With your background, I think you'd be very successful.
The value for you would probably be resume building, as opposed to personal growth. But if you're someone like me, who loves to collect professionaly certifications on their resume, you'll find value in having it.
I've got some free sample tests with about 50 questions on my website that will give you an idea of the difficulty of the questions. The only thing that might catch you a tiny bit off guard might be some of the client-server questions. A few about applets and a few about EJBs that may touch outside of the SCWCD or SCJP exams. Still, if you've been working with the technology for a while, which I assume you have, you'll be able to figure them out.