I was planning to do some photography with wildlife and was planning to sell my Canon Mrk2 70-200mm lens. However after discussing this I've been told that it's actually a good lens for wildlife (or can be). Since the camera I'm using has an APS-C sensor, it suddenly becomes over 300mm in reach.
Is it worth buying a lens extender to increase my zoom? The type of photography would hopefully mean the animals aren't more than 5-10 meters away from me. I've been told that the Canon 2x extender is pretty bad, while the 1.4x is pretty good, and for those who have first-hand on experience, I'd be grateful for your input.