Your question on the Compadre is a difficult one for me to answer, as I dont have a Compadre...when I read some of the posts relating to rings and jewellery found, I sometimes think that maybe I should get one, but so far, I haven't. As slingshot said, rings and fine jewellery can be found by most detectors from reputable manufacturers. There is more to it than the operating frequency and gain of a particular detector, although, in some areas under some conditions with some operators, these factors can come into play. Other factors that come into play are: the sites that are being detected; mineralisation of the soil being detected; the hardness of the ground and the detector operator's preparedness to dig; the amount of discrimination being used; whether the operator is detecting in discriminate mode or all metal mode; whether the detector being used is suitable for the conditions eg salt water; even the frame of mind of the operator can be significant.
From the posts I've seen, many of the areas detected with the Compadre seem to involve "tot lots". In these cases, extraction of the target is relatively easy, so a person might be more inclined to investigate every signal on the detector.....such areas are also conducive to the loss of personal items, including jewellery, toys etc.
From what I have read, there is little doubt that the Compadre will find goodies, and at a pretty good depth. Whether another detector in the hands of another operator would find the same goodies is possibly a question that we really cant answer.