Great article. You are 100% correct with your thoughts. In my experience it is important to try or test and measure multiple channels to work the channel that gives the best Marketing Return on Investment or MROI. However a lot of businesses then fall into the trap of just using the one single channel that has the best MROI or often cheapest cost). Its always best to continue to use the two or three best channels and then calculate an avg. cost per new customer and build this cost into budgets. That way as you say they are not reliant on one way to get new business.