I have had the x1 for six weeks or so and love it. Today I ordered a Periscope. So, while I can't extoll the virtues of latter, I can talk about what I think that it will do for me.
The x1 is a no-brainer. You flip a switch and you have a probe that acts just like a search coil on your XS, as to include discrimination and pinpointing. The probe is simple to use because you already know how to use the Explorer. Ralph at Sun Ray also has awesome quality control which means that the x1 is superior at all levels.
That being said, why did I just plunk down $549 for a Periscope?
Well, I am doing it because I am pretty certain that I am passing up a lot of targets. Have you ever found a spot with an iron sound that just reads a little higher than iron should? Well, I am discovering that something good is down there about 20-25% of the time, maybe a little lower. I am getting Ott's Periscope so I don't have to dig 5 holes to find one coin.
Another reason that I am getting the Periscope is because it is flexible. I have a Garrett that is frankly much quicker and lighter when it comes to snagging the new stuff - recovery speed is sometimes more important than vacuming up every penny. And who knows what I will be swinging 2 years from now!
Finally, you need to think of the Periscope as a metal detector - not a probe. It does everything a quality metal detector does. And, if you were so inclined, you could grid an area and detect it without a standard detector. I know of an area with insane iron density that I am going to section off and detect with the Periscope - just for fun. And nugget hunters use it to get into cracks and crevices that nothing else can reach.
If money is no object, both is a good answer. I doubt if either probe will disappoint you. I know that I spent a lot more time talking about the Periscope, but every bit of it is a summation of my hopes - not experience. I regard the x1 as a mandatory tool. I <i>hope</i> that I will have a similar feeling for the Periscope.
Aside from the s1, I am not aware of any other probes worthy of consideration.
Tim