Well, it's a whole different animal. It might give you a little peace if the flutey sounds of the Explorer bug you from time to time. It has a different and unique set of tones and there aren't as many of them...17, in fact...1 for each frequency. And there's a very distinct sound to a silver coin and a very distinct sound to a gold ring. I prefer the sounds of the Sovereign to the Explorer, I do believe. It also doen't allow as much tweaking or as many choices in discrimination. Simplicity and straightforward performance are it's hallmarks. It's maybe a little easier to swing, a little better balanced. It's a very solid performing machine and a nice backup or alternative to the Explorer II. Will it set your world on fire? Not likely, given that you are a happy Explorer II user. Will you adapt to it and find it to be a cool and fun machine to hunt with? I would bet so. Many Explorer users have Sovereigns and many prefer them. And of course that goes the other way as well. If you are hung up on the part of your question that asks what it has that your Explorer LACKS, the answer is not much. For most, it's what it DOESN'T have that makes it apealing. They are killer beach hunters, great relic machines, and nice silver seekers. Which are all things the Explorer is good at too.
If you truely LOVE your Explorer, you may not need any other machine. A few years ago I had my CZ-70 and I thought that NO other machine could ever compare. I used it for EVERYTHING...relic, silver, beach. It excelled at all of those things. I always said that if I could have only ONE MACHINE, that would be it. And then, just a week before the 4th Of July weekend...our biggest beach hunting weekend...my beloved CZ crapped out on me and needed to go back to Fisher for repair. There was NO WAY I was going to be without a machine. Well, it has a lifetime warranty, so no problem there. But I saw that I HAD to have a backup machine...this just wasn't going to do. I originally planned on getting another CZ-70. But then I thought of all the times I had admired the magic and mystery of the Minelab machines...all those frequencies. As well as the horrow stories of the dreaded "learning curves". But I decided that variety was the spice of life and took the plunge and got a Sovereign Elite. And I hunted alll summer with it and absolutely KILLED at the beach with it. I had nights where I came back with so much change, rings, watches, etc. it was unreal. In fact, my very first night out with it I pulled 5 rings. And from then I was hooked. I still have the CZ and would never get rid of it. But my main squeeze for the beach now is the Excal, the Explorer II for land, and the CZ in hot standby or for when I want a change of pace.
So why not go for something a little different? Try a Sovereign GT. The bang for the buck can;t be beat, that's for sure. And if you get it and try it and it isn't your cup of tea, as long as you take good care of it you'll get back most of what you paid for it and then go back and try something else.