As far as the CD material goes, I found that my son enjoyed using these simply because they broke-up the monotony of the pencil & paper approach. For this I was grateful! Every question is timed which made the experience much more of a challenge - my son tried to beat his personal best time of 11 seconds for one question! The multi-choice format also serves-up useful hints on answers even if you're preparing for the standard paper. This was a source of some discussion We used these some 2/3 weeks before the actual exam (TODAY!!) and felt that they were of use. Shame that there's no discount for those of us who bought all three packages!
PS ... My son claimed that the NFER paper as sat today was much, much easier than that of the standard of the CD and the IPS papers - maybe he was just trying to please his dad!?!