A good reason? I upgraded to 5.20 in the spring and first thing I noticed was the middle preset on the frequency with the HF coil was slightly higher. I didn't notice any big change in performance. Until two days ago.
I was doing a heavily hit salt water beach, and as the tide was going out, switched from my favorite Deus Fast to wet beach, with no tweaking. On the older version of the software it wouldn't hit a target more than 5" or so and was very chattery in the salt water.
Not anymore. I was shocked to find out the chatter was gone, it ran silent and deep. I was getting some targets at least 10 inches down.