My first question would be to ask if you were able to "check" any of your buddy's targets before he dug them? No offense, but if not, we can't determine if the reason he finds so much more is due to the detector or "operator error". Secondly, comparing the E-TRAC to the CTX...... IMO, both Auto and Manual are "hotter" on the CTX than on the E-TRAC. In head to head comparisons using comparable sized coils, I found the CTX 3030 was able to run two or three "clicks" higher than the E-TRAC, without falsing. In other words, if I were to run my E-TRAC with a manual setting of 23 before it chattered, I could run the CTX 3030 with a manual setting of 25-26. If the E-TRAC chose an Auto Sensitivity of 22, the CTX 3030 would generally select Auto Sensitivity of 24-25.
Manual or Auto? Auto Sensitivity is based on three channels, as analyzed by the CTX. Manual sets all three channells the same. As to which is better..........opinions vary..... But for me, it is site dependent. If I am in a site with few targets and minimal trash, I will implement Manual and crank it up until it chatters......then back it off one click. But if I am detecting where there are multiple targets, lots of ferrous targets or lots of modern trash, I'll select Auto with an offset. And that offset is dependent on how much trash or the number of targets in the ground. The more crap in the ground, the less the offset. Generally, for the sites I hunt, mine is at +2 or +3.
If you have too much Sensitivity selected (manual or with the offset), the transmit signal will be reflected back toward the receive windings of the coil, causing you lose depth and stability. I hate to use the old analogy.... but it is much like driving in the fog with your headlights on bright. You see farther on dim, with less light refected back into your eyes. Similarly, a detector can detect deeper if it doesn't have to deal with an abundance of signals being bounced back.
As to the calliope.... Unless you change the discrimination Pattern, the CTX 3030 will still make a tone on every accepted target that it is now. But by using fewer tones, you may not feel you are at the circus. I'd suggest you try out the Combined audio profile. Combined allows you to hear one of five tones. One tone is assigned to ferrous type targets. And the conductive side is broken down into 4 different "bins". You set the parameters of each bin. You set the level of the ferrous line. And you set the tone for each bin, based on tones that sound good to you. HH Randy