I'm not opposed to the whole 5 post limitation.  It makes sense that you'd want people that are going to be active on the forum.  The other side of that is like many of you have mentioned.  You'll get quite a few single garbage posts.  The 4 hour limitation is more of an issue imho... but then again it does force new people to browse through the forums a bit and possibly learn the answers to some of the questions that they might have.