I guess I should have been more clear...
I wasn't suggesting that he use the test pool to "study" for the test, but rather for him to judge for himself how difficult he thought it was by looking at the actual questions compared to the Technician questions.
If he passed his Technician test on the first try with a comfortable margin, then in all likelihood he probably won't find the General test to be significantly more difficult. If however, if it took him 2-3 or more tries to pass the Technician test with a minimal passing score, then he will probably find the General test to be a bit more daunting.
I totally agree that using one of the books mentioned is the best way to learn the material and then use the question pool (or an online test) to gauge your progress.
Either way, good luck!