A friend of mine said that ACER booklets were much easier than the real UMAT. I also had a talk in my uni from ACER lady and she said that ACER online booklets are dated back to 2006 / 2007, and UMAT is getting harder every year, so I would imagine ACER booklets and organisations who have similar test papers are not all that relevant, but on the other hand who knows, there is so much controversy around UMAT and everything else that comes with it. I checked UMAT sample questions from NIE website and they looked very similar to the UMAT I did, especially section 3, I must say I was quite stunned and it got me wondering at the end if I should have purchase their course to prepare.
Also, in relation to the other two courses you are talking about, my teacher in school said that you will always come across different comments on forums about different courses. E.g. a students that would do well in UMAT would not likely go and post a positive comment about a course they did, but a student who did not do well and spent lots of money on preparation is likely to go and post bad comments, and I think that is why there is always such a big mix of comments about courses like medentry, face 2 face, NIE, medstart, etc etc. I think what's important is that organisation you go with should be based in Australia or New Zealand at least, but definitely not overseas, and lots of those organisation are overseas and simply produce poor quality material and they are just out to make money. I recall my teacher was trying to buy some UMAT prep materials for our school, and she said when she called this particular organisation she actually was transferred to another country and the person who answered hardly spoke English and just kept saying how they need to create online account to register for the materials, just need to be careful I think.