I own an AT Pro.... love it. I also have a Tesoro.....love it. (not a Cortes or DeLeon)
I often wonder why so many AT's have hit ebay... agree most of this may come from early production problems. The other may be that it is a mid range priced machine that offers alot and appeals to first time users, it didnt break the bank too bad, but then found out that detecting was not their cup of tea....for one reason or another.
The AT is not a Lexus or Mercedes. It's more like an old Jeep (or insert favorite off-road vehicle). Goes everywhere. This is one reason I bought the AT over a Tesoro ID machine. I dont have to worry about it. Rain, submersion, silt, sand... it doesnt get in through connections or the battery compartment. It actually runs much more stable on wet salt sand than other machines I have used (tried to use) in the same situation.
I love the roll tone on the machine.... I never used the standard mode at all.... takes getting used to... but I dont dig caps with that machine. Wish I could say that about the machine I spent twice as much on.
The only thing about the AT that I wished it had was a backlight and a tad larger VDI # display.