Personally I have found that reading many different books on the subject of LoA has been beneficial. LoA requires more than just a new way of thinking... it requires a new way of UNTHINKING. In my mind there is a lot of things to unlearn. Reading many books on LoA reinforces the new way of thinking... even if those books do not offer any new insights. I can see a problem in reading many books if one was to take them in an extreme literal sense, because many of these books say "this is the way" and "this is not the way" or "do this but not this" (like read other books) which may only cause confusion. But if one can distill the LoA principals which are at the heart of the instructions in these books, I believe that they cannot hinder ones advancement. There are some things in the Science of Getting Rich which don't "vibrate" with me. There are many things that do! (Some of these may simply be an archaic form of writing or principals of the authors society coming through the book... I'm not sure yet). But regardless... I can see the principals of LoA in which the various authors are discussing, and I believe that more exposure to these can only help instill them in my mind.
I hope that this makes sense... LOL
Cheers all!
Chris