Hi there,
The emphasis on given subjects on the the real exam is variable, therefore i don t think you can predict the difficulty of any given exam. Concerning the sources that you mentioned, I think that( at least in my case) the actual exam was much more difficult than both of them. I did pass, but since I haven t received my score report yet, i can t tell you what the score was. I had an average 70% in q bank, and a 75% in the released items, if that s of any help to you. I would say that q bank was more difficult than the released items, and therefore closer to MY exam. Additionally, it has much more questions, so I think it gives a more spherical represantation of what may be asked. A friend of mine got 73% on the released items, and scored 83 in step 1.
Hope it was helpful,
Theodore