Well, the questions will have changed, but the basic theory, rules and regulations, and the particular items on which you will be tested will remain pretty much the same, just worded differently.
The bottom line is, if you have actually mastered understanding the fundamentals, as opposed to trying to memorize the questions / answers (evidently some folks have a much better memory than I), then you should be good to go by simply taking the new on line practice tests to familiarize yourself with the new questions, then go take the actual test.
The new test starts effective July 1, so you still have plenty of time to take the current test. However, if you choose to wait and take the new test, and have purchased the new Exam Guide, you should be able to sell it and recoup at least half your investment (if you don't mark in the book).
As a VE however, I always recommend studying from the book covering the proper exam dates. It is just one less problem to have to contend with.