Wow! Ted, you sure do pack a loaded question!!
Well, it's like this - technology HAS improved, and greatly. However, detectors can only go to a certain depth. The newer technology has been in trying to find technology that more accurately tells you what's in the ground before you dig - whether trash or not. For more money, can get a machine that tells you the type of coin as well. On ALL detectors, gold and aluminum are going to come in about the same. A lot of price difference is going to deal with warranty - 1 year vs. 5 yrs. vs. lifetime. Probably the best inexpensive detectors on the market are the old-technology Tesoro detectors. Almost none of the Tesoro's have any display whatsoever. I think one model has multi-tones. Also, they are 100% analog rather than digital. The best Tesoro on the market can see into the soil about as god as the best digital machine costing thousands. So why do so many people go with digital? Because they have this belief that newer MUST be better. And in some cases, it truly is. Some folks just aren't "wired" for using a single-tone, no-display detector. Other people (like me) aren't "wired" for technology that has to work harder than necessary.
Wait, work harder than necessary? Yes. Every detector out there creates an analog signal. Every one! The digital models, however, then change that signal into a digital signal, THEN try to process that signal by means of a digital display and/or multi-tones. What the older technology has that newer technology doesn't is that once you've gotten used to "listening" to your detector and understanding it's language, analog detectors have many more nuances within a single tone than high-priced digital detectors costing many times more. There are people that are VERY fluent in the language of their detector that can tell with better accuracy what is in the ground, even though they have no display or multi-tones. But it takes practice - LOTS and LOTS of practice!
Your older Minelab is going to be a good machine. I don't know how it compares with current Minelab's or other makes/models, but it will still do the job it was built to do - find metal.
That's about all I can tell you....and even these words aren't the voice of "MY" experience, sadly. But these are the words that have been repeated over and over and over, not just on Tnet but also many other MDing sites. Therefore, I trust this post to be true - though not necessarily all-inclusive.
....And also, the deeper a target is in the ground, the more difficult it will be for ANY detector to tell just what the target is! ...Kinda like when you get old and the vision isn't so good anymore - up close you may see just fine, but things get more fuzzy the farther out you hold it.
