Plenty of people have heard of them, they first came out in 2001 and lots have used them but overall I think the Tejon, Vaquero and others were more popular than the Cortes or Deleon, the only two models with screens.
Ask a crowd of Tesoroheads what they own or have owned and these two probably will be near the bottom of popularity.
Still, they are Tesoros and have their fans and if you swing, listen and learn it you will have a good knowledge base to utilize it you want to switch from this to another Tesoro or even another brand.
I have used Tesoros for hundreds of hours, learned the language and and then got into screen units like an F2, F70 and now a Nox, despite the screens it is the tones that matter more to me when I stand behind them...any of them.
I have always said learning to hunt by sound only will be an advantage to you no matter what brands or kinds of favorite detector you end up standing behind
In the future.
You got a screen on yours, honestly I don't know if I would ever look at the thing if I owned one.
Hunting with Tesoros is a Zen thing for me, me, the detector, my thumb and the disc knob...and those tones.
I walk, I swing, I listen, I thumb the disc over targets to figure them out and I dig certain targets that meet and stay within my strict rules for digging.
I used to dig a lot more trash, over the last few years I got tired of that but I found as I got better at understanding and using my detectors my ability to ID trash and avoid it got way better.
I now dig a whole lot less trash than before but I still find more than my share of treasure.
At first all Tesoro beeps to me all sounded the same, as time went on they changed and became much more expressive and information filled.
actually they didn't change, I did...I got better at all of this.
That GB...it only works on the all metal side, in disc it is preset and you can't affect or change it.
Here is the manual, reading it I think it is a pretty neat tool.
http://www.tesoro.com/info/manuals/current/cortes/
Maybe it wouldn't be my first choice if I was a shiney, brand new newbie but if this is all I had to work with there are way worse and less capable units out there for sure.