I had a Cortes, and I found the depth pretty impressive. Not Tejon impressive, but better than the Golden uMax I had at the time. I found that if I saw a 95 flash even once while swinging over a target, even though the numbers jumped around, it was a coin. Being in Canada, I couldn't rely on the markings for the US coins. I found the SUM feature not very useful. By the time I kept swinging to get the tones to average out I could just dig the target and not have to guess.
Battery life was incredible. I was able to get 50 hours out of a set, even with some occasional use of the backlight.
My only real complaint about the Cortes is that it is overpriced for what you get. As much as I love Tesoro products, I have to admit that there are better choices out there for the money if you feel you must have a TID machine.
Have fun with it.
Dan