Though this question was meant for Kathy & Bert let me try to add my opinion here.
Its up to the individuals how they work on the examples and if you can use WL (or any other commercial server) its even better as you would not be using the RI in your real job. I myself am not caring much for the examples in the book as such since I work on a real
ejb project (under WL8.1) in my job. I try to compare and review what I am doing at my work with the HF EJB content. That should be enough for the SCBCD and to understand whats going on behind the scenes.
My 2 cents.
thanks