Since this thread has been merged with another and moved at the same time seems that some replies have been mixed around.
My PERSONAL comments were about 'cockpitweb' software. Please be aware I have never used the 'PILAPT' software and therefore can not comment on it.
However I have to disagree with 'poss', that margin you talk about completely depends on the individiual person. As you righthly say they help in confidence and familarity with the type of tests and skills involved so why not give yourself the best possible chance and use them. For some people they may only help slightly but for others they may help alot either way it has helped!! This maybe the difference to pass/fail. They are by no means a garantee to success on the day but iv not come across anyone who has said they did not help what so ever, usually if its negative feedback it tends to be because the tests on the day were not exactly the same but these are not the specific airline tests so how can you expect that in the first place. Its just a means to practice, gain familiarity and confidence.
Trust me Practice does make ALL the difference. Iv seen it first hand and with my fellow colleuges in the airlines. Like I mentioned before I have only used the cockpitweb software and if you read my previous post I mentioned it helped significantly with the BA selection tests. Though the tests had slight differences they were very similar, just make sure you read the instructions carefully on the day so not to get caught out!!
It may not work for you but certainly did for me and others I spoke to.
Good Luck to all!