I currently have the Canon EOS 550D with the 18-55mm IS kit lens. I am primarily looking for greater telephoto reach, as I have found the 55mm length to be quite limiting at times. So, I was considering the 18-200mm IS lens which would be a good general purpose replacement for the kit lens, versus the 55-250mm IS lens that would give slightly greater telephoto reach while complementing the kit lens.
What are the pros & cons of each like optical quality, effort in changing lenses etc, considering the fact that the 18-200mm lens is almost 3x as expensive as the 55-250mm one?
Note that it's highly unlikely that I'll be printing photographs larger than A4 size.