I heard the major difference between "Oracle Certified Expert WCD" and "Oracle Certified Professional WCD" (SCWCD before) is the former is based on JEE6 and later is based on JEE5.
Have studied for Oracle Certified Professional WCD exam and will it be advisavle to take up the Oracle Ceritified Expert WCD exam...
Short answer: yes you should take the new JEE6 version if you dont care the score.
JEE6 exam has some new topics but lower passing score (60% vs. 72%), so even if you dont know about the new topics you will pass if you are well prepared for JEE5 exam.
But thats only my opinion.