In the past I tried at least 3 of these applications, but they mostly were full of bugs or didn't work properly. The search function was mostly corrupted and when you searched for very broad keywords, it either didn't find many results or returned too many results with nofollow or low PR, and I specifically instructed not too! I don't mind if the software is slow in searching...all I want is results!
I tried comment kahuna, real link finder and another name I can't remember. So before I go out and buy something, please share your experiences with me and with some details if you can.