After a year of postponing it, almost on the voucher deadline, I passed the 310-091, which in the meantime changed its name to 1Z0-860.
Long story short - I started to learn about four weeks ago, by skipping through the Manning's "EJB in Action". I considered it to be too exam-unrelated, so I went on to read Wiley's "Mastering EJB3 4th Edition".
I found it much more relevant and suitable to my certification needs.
About a week ago I started learning using sample questions as the basis. I used all mocks listed in the Ranch's links list for SCBCD, all free ones, and some demo versions. All doubts I had were quickly resolved by Mikalai Zaikin's Study Notes (thank you!) and EJB specification.
Just before the exam I came across the Oracle's sample questions for 1Z0-860. I was terrified by my results - just 50%... Maybe I was tired, I don't know... Question in section 8.8 has its own thread here on java ranch, question 3.3 has errors - it confuses stateless and stateful beans...
Now good news for everyone who wants to pass this exam: there are no such questions on the real exam. They are not so puzzled, they do not contain so many errors or ambiguities. In fact, most of the questions are quite easy if you know a bit about the subject. In my opinion it was easier than SCWCD.
So, thank you all for providing information on mocks and recommended books.
Good luck to all future SCBCD/OCPJBCD exam takers.