I had heard a lot of people complaining about Centech harnesses being hard to understand and how it is hard to follow the manual.
I have absolutely no experience with Painless, because I didn't want to shell out that coin. But, I did go with the Centech. There is some cutting involved, but I in no way see how it was that hard to follow. I even have a different setup with my aftermarket EFI system, and I didn't think that it was too bad at all to get everything wired up. The Centech is a very nice harness that has everything labeled on the wire for you. I thought it was pretty straight-forward, myself. Maybe I just have a newer version, or something.
I just can't see how Painless could be so much better that it warrants the drastic price difference.