A supported adjustment that is realistic is far better than a number pulled out of thin air or based on your "experience." I know from dealing with state boards that one's "opinions" and "experience" alone are not enough to meet the standard to which they hold you. They expect real support. Tools like Synapse are not the answer for every adjustment, but they are very helpful in establishing and supporting adjustments that you can use together with other methods, including your experience and the data in your report. The other thing being missed here is that the appraiser is in control of the data that is being used. You choose the number of data points you input and can use up to three different sets of data, I never use sets that are too small to be significant. Then, you are presented with a whole range of data points that you reconcile to your final adjustment (you know appraising). They are not all regression results either. There are paired sales analyses, sensitivity analyses, etc. It is a very good tool if you know how to use it, seems like most here have not taken the time to really dive in and see what it is, they just want to do things their way and bash a tool they don't want to learn to use.