It is not that I "doubt" you, but you state things that are facts, and back it up with the fact that you do R&D work for nuclear systems. This still makes your "opinion" and not fact. Fact is some thing that can be proved with good research and scientific tests, and decent ones at that. When I see the links to such tests, I will buy them as facts, and until then, I will take it as opinion.
You state that the ACE will not work well in soil with high mineralization, and yet it does still make those finds. I can not say if it works as well as other models, as I have not used them. I have found no problems with the speed of the ACE however, or its recovery time.
You seem to like to crap all over the ACE. I guess I can understand that, since you were once a paid employee of White's metal detectors. However the ACE is a good machine for the money, there is too much evidence to deny that. It will work in highly mineralized soil if you know how to work it, and from what I hear it will also work in high salt beaches, if you know how to work it. These areas are not its best, but it WILL work.
Manual ground balancing may be best for you. You have a high degree of understanding about detectors and they way they work. That does NOT mean that this is also best for everyone in the hobby.
I agree, the ACE is certainly NOT the best machine for you. I think there are few of the GArrett machines that would be. You are best outfitted with a machine where you have a higher degree of control. That does not mean that the same applies for all people. I prefer to work most programs I work with in Linux, and in the terminal, but this is not what I would recommend for everyone.
You don't have to go real slow with me. I can hold my own with anyone. WHile I am new to this hobby, I do get the theory (though I would like to know more about it). As I said, I can not attest to how the ACE works relative to other machines because I have not used any others. I do know that I have read many opinions about these machines, and I have seen the things that people have dug up. Assuming that these people are not lying, then all the machines you mentioned, including the ACE, work, and they do a good job. Perhaps the ACE does suffer from a slower recovery time verses other machines. I would not know, I have not tested them (nor have I SEEN any tests). I do know that the recovery time for the ACE seems just fine for the hobbyist getting into detecting. What I am not sure of is why you seem to insist that the machine is garbage, when it clearly is not.