I've used the AT Pro for 1 year now and average about $40 in clad a month. Silver, not so good. Last Feb (2011), I reported to Garrett that I hardly get coins deeper than 6-7", I have gotten a few at 8", but the signal was all guess and sounded like iron. I made a depth test video for Garrett and wanted the unit back. They sent me a new one. Same results on depth. They wanted it back too. They sent me another. I've 3 different AT Pro's to test and they all give me the same results, 6-7" max.
You can watch the video on my youtube page. It's very simple, I throw a half $ in a hole @ 8" and the detector doesn't see it. I also buried it for 3 months and still not finding it.
But others will tell you they get 8-12". Maybe they do in their soil, who knows. I measure my deeper digs and I know what I'm getting here in Oregon.
I've done side-by-side test with an E-Trac and recently, my friends E-Trac hit a 7" penny, but I couldn't. That's pretty bad. But all-in-all, the AT Pro is a good unit for general hunting. If you watch the video, I can't find the silver half with the AT Pro, so I've purchased a used E-Trac from the classifieds here on Treasurenet and it should arrive very soon.
The cost between a AT Pro and E-Trac is 3:1. I paid $600 (Kellyco w/free garbage) + $125 Garrett Pro Pointer. I also sent in 2 AT Pro's, which cost me a total of $50. Total spent = $775. I purchased the E-Trac with Sun Ray Probe for $950.
I will be doing many comparisons, but just from what my friends can hear and I can't, the E-Trac is a much deeper detector, but it cost more. If I could go back in time, I would have not bought the AT Pro. It's nice to hunt in the rain and get in the water and not worry. But I honestly didn't do much water hunting. Not like I thought I was.
I'm only responding from what I know here in Oregon.