Pros and Cons of using an Oval Chainring?

I'm a big fan of Absolute Black Oval Chainrings, especially for mountain biking where you often have an uneven pedal stroke (unlike road riding where riders will usually have a more perfect pedal stroke).

Here are the Pro's and Con's of riding with an Oval ring:

Pro's of Oval Chainring
- Efficiency of your pedal stroke
- Can help to increase traction by smoothing out your pedal stroke
- Can be really good for people who use flat pedals, because it's harder to have equal pedal stroke
- Can help to reduce knee pain

Con's of Oval Chainrings
- Can wear out rear derailleur / clutch mechanism faster due to chainring causing the chain to stretch unevenly as you pedal.
- Chain guides may be limited (However, Absolute Black makes narrow wide chainrings, so that can offset the need to use a chain guide in most situations)