I would also like to add that, at least for me personally and speaking in sweeping generalities which I don't like to do; I feel less secure with "closed code" than "open code".

For me, I can easily trust what I can see. I can search open code more easily (and look for problems) than I can search a binary or encrypted code like encrypted PHP (which I cannot search at all).

Recently, I refused to install encrypted PHP on a web site for that exact reason. I do not trust code I cannot see and see no reason to install encrypted PHP code when I can find open alternatives.

As I mentioned before, I don't normally like to respond to generalizations without context, so I am simply providing my personal opinion, and that is that I (my personal opinion) feel more secure when I can examine the code, grep it, search it, add debug statements, etc.