Here is one general relationship which may enter into this discussion. When metals - or any electrical conductors - are heated they become more resistive, not less. As they are cooled they become more conductive. If any experiment depends on electrical input, as do all electrolysis experiments, then the unavoidable result is that nascent positive thermal feedback to the overall system reduces conductivity which reduces current delivered. The early stage of positive feedback is either squelched or proceeds to failure if it is strong enough.
Of course, there is a unique claim for one LENR system which needs only thermal input – the original Rossi device, which is the only system which can truly benefit from positive feedback. In fact, his E-Cat system demands it. Electrical loss from higher resistivity is avoided. There is a preferred and well-known negative temperature feedback mechanism in normal electrodynamics but there can be a blip in the curve having DIFFERENTIAL positive feedback, as in Miles case, where things would be reversed from the normal state in a narrow range. It could lead to a runaway or meltdown if it was more than a blip. There are four or five examples of runaways over the last 28 years. Because of rarity, the runaway has not been harnessed to increase COP since it is rare, unpredictable and uncontrollable other than in Rossi’s claim. Thus - there is no evidence of positive feedback being useful except for the infamous wet steam device and its successors which were claimed to run on thermal input. NO ONE ELSE has made this claim- other than Rossi. Miles may see differential positive thermal feedback over a part of the curve but he could not capitalize on it for increased COP. If feedback is not predictable or controllable then it clearly isn’t going to be integrated in a system in order to produce higher COP in the last stage which was Alain’s original presumption. Rossi provides the only evidence for positive thermal feedback leading to higher COP. Anyone who accepts the positive feedback modality should realize that it comes with a lot of baggage.