Movin' On

I'll be the first to admit that I was a "tumbleweed Christian" those initial two years after my conversion. The biggest problem with such behavior is that no one can count on you to serve if you bounce from church to church every week. But the error pendulum swings the other way, too. Some consider it downright dishonorable if you change churches (especially if it's from the critic's church to any other) more than once or twice in a lifetime. Unless you get a job offer in another city; then it's OK. So let me get this straight: God forbids changing churches except when somebody in another city offers you a better-paying job? Hmmm... 
After my tumbleweed days, I was a committed, faithful servant of one church for the next 17 years. But then I was a committed, faithful servant of three more churches in the last 13 years, and that's the time in which I think I've experienced the most growth in holiness and in finding and fulfilling my purpose* (while many saints get stagnant this far along in their walk with Jesus). I've changed churches lately at a slightly faster pace than Paul the apostle did. He was a faithful part of four churches in the first 14 years of his discipleship, which our Lord deemed good preparation for his first missionary journey. My point is that even the esteemed co-author of much of our New Testament would be labeled a church-hopper by some.
Moving on to another church can be of great spiritual benefit.
How?
You get stretched. Things you're used to are changed. You have to meet lots of new people. 
You have to re-examine your doctrines.
You appreciate differences of style within the Body of Christ.  
You learn better methods, or else you get to share the better methods with your new church.
You get to experience being the new guy again, deepening your empathy for visitors to the church and potential converts.
Of course there are things to be said in favor of longetivity within one congregation, too.
Some folks change churches because they don't want to repent of inability to get along with folks.
Bottom line: Obey the Holy Spirit, and don't make up rules that aren't in the Bible. 

*My wife and I are preparing to become missionaries to Muslims in the southern Philippines. We'll leave June 2013.