Both have a leaning curve with the Explorer a steeper one so either one you have to have some Patience. I have seen good coins and good depth on both of them. On the Sovereign the coins like a copper penny, clad and silver coins read the same tone and ID number. On the Explorer a silver quarter or clad will be a little different tone and ID, even a dime and a quarter will be a little different.
The tones on the Explorer are quick and back to a normal threshold while the Sovereign tone will stay longer until you go over a different target, so this makes it easier to hear when you go over a different target.
You can do more with the Explorer than you can with the Sovereign, but with the Explorer you have more controls to adjust for the area you are hunting while the Sovereign is more of a turn on a go detector.
Myself I do much better with the Sovereign GT than with the Explorer as I can hear the tones better on the Sovereign and understand them better, I also dig less trash and more coins with the Sovereign GT too. The reason is the Sovereigns hate iron, but the Explorer you can get some coins next to nails better. It also has more high pitched tone of nails that will fool you.
On the ID meter on the GT when you go over a target the numbers are what you are hearing at the time, with the Explorer you may be hearing the tones of a good target, but the threshold has to come back for the meter to ID it. The meter reads the last target the coil sees, so even though the tone sounded good while you are going over a good target the coil may see a nail before the threshold comes back so the ID will not be correct. This is why you have to go more by the tone than what the meters says.
I know of a guy that had a Explorer XS and didn't do very good and traded it for a Sovereign and did much better, then came the new Explorer XS II and he tired that with the dual digital number and still couldn't do good like every body else did with the XS II in his area. He tried it for 2 year and sold it as the Explorer was not for him and uses a Sovereign and does much better. The Explorer is not for everyone as we are seeing on this forum just like the Sovereign is not for everyone. I have heard those that use a Sovereign and go to a Explorer have a harder time learning the Explorer than if they never detected before or used a different detector.
In the last couple of time I been out i used the GT in a area i worked hard with the Explorer and was surprised at how much I missed with the Explorer, maybe the Explorer seen them, but I didn't hear the tone correct, but with the Sovereign I could hear the tones great.
Like I say these are both one of the greatest detector made, I have both and use both and like the finds I get with either one, but for me the Sovereigns tone I understand better as they are not so complected. I trust the ID on the GT better as I know what the target is as the meter is reading the tones you are hearing when the coil is going over it.