Its the KE Foundation, not Birmingham LEA, that has switched to using the Univ of Durham CEM for the 11+ tests. Birmingham still uses more traditional NFER type tests for Sutton Coldfield/Bishop Vesey exams.
Not sure about any other LEA at the moment, but we think Warwickshire is switching to the Univ of Durham CEM tests next time. They did a trial at Alcester grammar last year - all of their year 7 did an online CEM exam and Durham analysed the results for Warwickshire and made a proposal to run the new 11+ tests based on a number of options. They considered switching last year but decided to use NFER for 1 year only (they used Morey House prior to that but these were discredited as the actual tests used were in published for educational establishments)
In respect of different type of tests - yes variety is important so I would look at a range of conventional and E-papers many of which are available from this site at a pretty good discount. See
When my last child did the 11+ exam (thankfully a few years ago) we purchased as many different type of 11+ papers we could find and tried them all, often many times over. In those days it was a case of having to use a rubber to erase the previous answers; e-Papers help a lot now. However there is a much greater variety these days. For the KE Foundation 11+ an extensive vocabularly is essential - and perhaps more importantly the child needs to know the precise meaning of the words. The problem is that many children have a generally good vocabularly, but only a vague meaning of a particular word. This isn't good enough for the exam and the synonym section.
On the maths side, we found the NFER was actually quite good.
If you want to find out a bit more about the philosophy behind the Univ of Durham CEM have a look at their site and in particular their marketing material. You should be able to find this by a google search. I think the product is called GetINTU.
Take a look at some of the posts by fm and previously KE Mum in the Birmingham Forum.
On a separate subject, do you live in Birmingham or one of the adjoining LEA and do you have a son or a daughter? What KE School are you considering?
The reason I ask this question is that the pass mark for the various KE Grammars varies quite significantly between schools. I've monitored the minimum exam pass marks over the last few years and there is a distinct difference in terms of the degree of difficulty of getting a place.
It's more difficult for boys to pass than girls and this can have a significantly bearing if you live in a LEA than only allows 3 preferences on your LEA Admissions form (such as Worcs or Dudley). Please bear this in mind when making you preferences.