Depth was near surface to 6 or 7" on most of my recent finds.
I've recently bought a Sovereign GT as no larger coils exist for the QXT to maximize depth on coins. I know the Hot Shot exists but I couldn't get two brand new ones to function with the QXT Pro I had at the time. Forced with the decision to get a second machine that can handle larger coils for max depth on coins I decided to try one of these. So far so good. Didn't want to go back to the Explorer. Several things I didn't like about them, including the unbalanced weight with no ability to hip mount, which you can do on the GT. Depth is pretty much a toss up between either the Explorer/GT anyway. The one thing I don't like about the GT/Explorer is the slow recovery speed, but the iron mask feature is impressing me with it's ability to pull a good coin ID out of a coin laying with a nail, so that somewhat compensates for the slower recovery speed.
Currently I have no plans to sell the QXT Pro, as even hip mounted the GT is more of a workout to swing around in the woods. The 10" coil seems to snag every little twig as I go. Having to slow down to a crawl to hunt with it properly also limits my ability in some areas, such as scouting new locations. For those reasons, combined with liking to have an ultra fast recovery time in heavy non-ferous trash, I plan to keep the QXT. I plan to scout new areas with the QXT and then hunt it slower later with the GT, or as said use the QXT in really heavy non-ferous trash where the GT might have some problems unless I use a 5" coil or something. In iron it's kind'a a toss up in my mind right now...The fast recovery speed to sniper out the coins, or the Iron Mask GT feature to ID them that way while ignoring the iron. I guess either has it's purpose.
As long as I'm here, I thought I'd pass along a QXT Tip to anybody new to the machine. You can tell differences in coins by watching the display and listening to the audio. zinc pennies will mostly stay in the zinc zone. Copper wheats/indians will bounce evenly between the zinc and coin zones. Clad dimes will mostly stay in the coin zone but will hit into the zinc zone every 4th or 5th sweep or so a bit. Quarters will stay in the coin zone and have a much more fuzzy/warm sound to them than dimes. Silver dimes will stay in the coin zone but have a slightly higher pitch than a clad dime. Silver quarters will still act "warm and fuzzy" but also have a slightly higher pitch. You'll get good at this over time. It helps me to avoid zincs/wheats when I just can't stand to dig another penny, and also avoid clad dimes in favor of quarters or silver.
Interestingly enough, although the GT has a VDI that goes up to 180, it still lumps most coins into the 180 number much like the coin zone on the QXT. Copper or zinc pennies will tend to drop down to the 173 to 178 range or so. However, the meter's resolution with everything below coins is what most of the scale consists of, and it gives you much more ability to split hairs on things like gold rings, avoid certain trash targets, and so on.