I have used my Infinium on dry land for relics and in some freshwater. I like it but if you are not considering hunting salt water at all, I would probably stick with what you have. I have a Sovereign for hunting all locations other than Salt Water. Now if you are going to be hunting Salt Water, that is a different story. I have used the Infinium PI machine exclusively for Salt Water and I love it. It allows me to hunt quickly and I can concentrate on gold targets. Not that I don't like silver but gold is where it is at. The Sovereign I use on dry sand beach areas but the wet sand and the water belong to the Infinium. You get one tone for gold, a high/low ding dong doorbell sounding beep, and you get a separate tone for silver, a low/high reverse doorbell sounding beep. When in the water and wet sand, I concentrate on possible gold targets only. I can move faster that way and don't spend much time digging coins, etc. The Sovereign like the Excalibur gives a variety of tones which you have to interpret. Once you have used them a while, you get good at it but some gold does sound high like a coin and some gold can get down in the low low tone range and then there is everything in between too. The Infinium will give only the one tone for any type of possible gold. That is a good thing to me.
They are all great machines though. You won't find me saying that folks using the Excalibur should change to the Infinium. It is all a matter of personal preference. I have been at this business since 1986 and I have never seen a detector I didn't like. I just like some more than others but again it is all about personal preference!
Good luck!