Yes AF system alone worth the upgrade.But again that's depend on what you use for it. Most people confuse with what you need and what you want.
If doesn't matter if the new gear you can afford it or it's <10% from your income. If it doesn't serve your need or it has lots of features that you don't need it, what's the point?
On the contray, if it cost few months of your income, but by having that you could boost your income or take the shoot that you never has the ability to take before.
I am a professional, this cost is not an issue
The wife told me to order one to celebrate my retirement and birthday. Also it is a "thank you" because I saved her life last October in Jackson Hole when she went into atrial fibrilllation. Of course the real gift was just continuing to have her around. 
I've been unemployed since July 2010 so I had to 
