Wow, I am a bit surprised about your reference to tracking numbers being a positive. Tracking phone numbers that are not the genuine phone number to the business and used on their genuine website can mess up the client's NAP which is their very identity online. So I guess we will have to agree to disagree on that one.
We do track our services but through other proven, white hat methods that protect our clients' online reputations now and long-term.
Finally, many of our clients are small local business with very limited advertising resources. Many do not even understand the value of having quality content on their own websites. I guess I just would just rather see them invest in content rather than duplicate links.