When I bought my Equinox, it had version 1.75 on it...I updated to version 2 as soon as I got it which had just come out.
After using it quite a bit with version 2, I updated to version 3.0 and used it some afterwards.
For me the 4 khz did not really impress me... too many bad targets sounded like coins to me.
However, I did find one silver coin while using 4Khz, but I prefer using multifrequency.
I also seemed to notice that silver coins, especially dimes, did not seem to give quite the same sound as they did before updating from version 2.
I continued using it with version 3.0, but later mentioned this to another forum member and asked him if he noticed any difference and he stated that he did.
Shortly after our discussion, we both reverted back to version 2.0 and currently are operating with that version.
Since your detector came with the latest version, I would say keep it as there are no bugs with it... everyone has their own preferences.