Hey Vince,
I ran out of time but now I'm back. My comparison will be with my Tesoro Supertraq, and with my friends who use Whites.
I like the explorer because it gives you lots of accurate sounds. You can have awesome awareness of target composition, and depth by listening to the sounds. The detector can achieve suprising depths even when the coin is on edge. For example, the deepest coin I found that was at about an 80 degree angle was a barber dime at a measured depth of 8.0 inches.
Trashy operation can be tough for beginners. This machine allows you to listen and make decisions on the large numbers of targets that are present in trashy areas, so it can be overwhelming. With my tesoro, all I got was a small array of simple sounds with not much variance. Large numbers of trash items sounded like coins with my tesoro. With the XS, there are many variations of sounds (tone, pitch, texture, threshhold presence, signal duration, signal warble) that are produced. So this machine gives you the opportunity to do your own discrimination in your mind with very good accuracy. In trashy areas, this can be confusing. But in the long run, the variety of sounds becomes an effective tool for finding those coins even in "collected out" parks. I feel that the real value of this machine is in the sounds it makes.
I suspect this machine may be a little better than the top White's machines. For example, I found a verticle barber dime at 7 inches in a park. I left it in place in the ground. A couple guys with high-end White's came over and could not detect it. Also, the park I collect at is supposedly collected out if you ask all the guys running around with Whites. They don't seem to be interested in the area. I went in there with the XS and pulled out about 30 old coins over several weeks and over many many hours of hunting: IH, Barber Dimes, Wheaties, 1 Standing Liberty Quarter, 1 Walking Liberty Half. They were amazed and so was I. All the Whites guys were collecting at a nearby construction area that had the top 4-8 inches of soil removed.
In my opinion, the advantage of the XS over my Tesoro is depth, target separation in trashy areas, and target identification. The disadvantage is that the XS has greater weight (I must switch hands all of the time). Another advantage of the XS is that it comes with the rechargeable battery. I have spent over 200 hours with the XS and never bought batteries for it! Another benefit of the XS is that now I dig less trash and more old coins than I dug with the tesoro. Although, when I was trying to decipher rusty nails vs. silver coins over the last month, I dug loads of rusty nails!
Mike