On the deeper coin signals, in my test garden the 6 and 7" coins (dimes) comes in loud and clear after Super Tuning and Power Balancing. However on the 8" and 9" dimes the Vaquero will just click or sputter so to speak and sounds just like iron to me. I probably wouldn't investagate this signal out in the field it sounds like iron so much. However, if I turn the ground balance 1/8 turn more negative, again this is after Super Tuning and Power Balancing, it will give a good beep but it still has a click or sputter only it's a lot more fainter. The more positive beep, sounds good enough to investage as a deeper coin.
On setting the discriminate, the more you turn it clockwise, you do lose depth. If I turn the disc. down to AM (not clicked into AM) I can barely hit on a 10" dime, but when turned to the mark just below 5c most of the time no signal at all, but this is in sandy loam soil (50% sand, 50% native organic soil)
Hope this helps.
Ron