“If your not using a productivity tool, you’re ripping off your customers and wasting your time”
While I have met and worked with many ReSharper/CodeRush users in the past and talked about the value that such tools add, the sentiment has never been so strongly expressed. I have been playing around with both the tools over the last several months and am a happy ReSharper user now. I found CodeRush to have a lighter memory footprint, but the graphics and effects just got in the way of my work. ReSharper, on the other hand, was very usable and intuitive and had a minimal learning curve. Your experience might vary, but I would encourage you to take both the tools for a spin and try using one, if you are not already doing so.
Coming back to David’s statement, I think I agree with him more or less. Not only can you save some serious time by using such a tool, these add-ons generally encourage you to write cleaner code. You also deliver more value to the client in less time, and that could possibly lead to better feedback, more projects or recommendations to other clients.