You may want to try compton-git instead. It is a fork of xcompmgr-dana and handles transparency very well.
Wow psychadelic!I found xcompmgr to be rather buggy when I used to use it. Try xcompmgr-dana (dcompmgr I think) or Compton. I used to use Compton and it worked pretty well.I stopped using real transparency in favor of pseudo-transparency because I sometimes use the tabbed mode on multiple terminals...