Hi DF: You are discussing one of my primary metal detecting interests here. Regarding the industry being in a state of transition, I sure hope so. I think that you can only come up with so many new bells and whistles before the detectorists say, "What's new?" I think it is very similar to the auto industry. As long as there are plenty of customers who crave these machines, there's no motivation for real technological advancement. "This years model comes in Pearl color and has a 55 speaker system, too." But the public, at least here in the U.S., are starting to get tired of the "New, but nothing really new" offerings. I think it is a generational thing. The baby boomers accepted a certain level of technology, and that was that. Now we have new generations who feel (quite rightly) that we could do much better in the designing of these things if we really wanted to. And they are starting to demand it. So yes, you will probably see some manufacturers disappear, as they were more focused on marketing than on real tech innovation. Other companies will arise, or transform, out of necessity. The new generation is basically saying, "We can put a man on the moon, but I have to buy this obsolete technology?" So yes, it is more hype than anything else right now driving the market. I find it interesting that many detectorists feel that it is impossible to design a metal detector that could do this or that. I guess they are content with the current technology. I never was. I always felt that most of these detector companies were having a hard time thinking outside the box. I know that designing and marketing a completely new type of detector is very risky, and "Let the competition introduce it first" is the current philosophy.
Overall, I would say you are right about the manufacturers that you cover in your post. I'm not an expert or even a dealer, but I have been involved in TH'ing for many years. One thing that I think I would have to disagree with you about is Tesoro. You are right in saying that most of these companies are about the same, just as a Ford or a Chevy is. But from what I gather, Tesoro makes detectors that are better than average. And you are right about MineLab being in sort of a class by themselves. But they are not THAT much better, and they are very pricey. More hype. I think things will start to develop soon, as detectorists becomes more discerning and demanding. How about a detector with a MP player in it? (Just kidding) I think that some GPS technology in a detector could be useful, though. Just as the American public is starting to become much more discerning and demanding about automotive technology. Just don't hold your breath.
Happy hunting, Kevin in Ipswich, Mass.
Disclaimer: The following is just the opinion of the writer and is not meant to discredit or recommend
any metal detector companies. 
It seems the industry is in a time of transition. Whites has discontinued a fine series of detectors called the Pro Series and has introduced the Prisms and Matrix M6. It is my prediction that the Matrix series will prove to be unpopular just like the Quantum series was. Used Spectrums, Pros, and Eagles are going for unusually high prices on Ebay. Garrett remains about the same continuing to produce ugly green and yellow detectors that feel uncomfortable and seem to lack depth. Fisher has sold out to Bounty Hunter. They should have stayed with the CZ and 1200 series. Tesoro insists on naming their detectors after the Spanish tradition and the new detectors are cheap looking but colorful. They probably perform about as well as any. Bounty Hunter shows promise. Their service department is excellent. Detector prices are reasonable but their units look like mufflers on a stick. Most of them have a notch and auto notch mode that people dont use much. Minelab continues to be good detectors but overpriced. Troy is working on some new models. Compass is trying to hang on. Lets hope the future is better! HH , DF.
