I love my old Discovery 2200 and my F-75 is a dream machine (hate the AA batteries) and I saved my pennies and bought a 4th generation Time Ranger (I love it too). Ya know that old Discovery 2200 cost me $35.00 at a garage sale and once I learned to listen to it I could hunt with and sometimes outhunt the 'big boys'. sure the more costly machines have great features, but are they really worth it? Not always (in my case and opinion). When I swing the 75 I use the trigger for pinpointing and ground balancing I love that, but you have to really stop and think about things like your: Sensitivity, Discrimination Level, Process#. I find myself spending more time looking at the machine than the dirt (it is cool to look at). Now my brother actually uses the machine (unlike my watching it work). On the Time Ranger I live for the SNIFF (to target specific object types) and BLANK (to ignore specific objects). I also spend a lot of time missing many contacts because of those features (thats a good and bad thing). The low cost low featured Discovery 2200 remains the unsung hero throughout it all. It has just enough features to force you to look at the screen once in a while, but not enough to captivate someone (even someone as simple as myself).
If learned a lower priced machine can and will perform with the costly ones. Will you miss things? Sure it happens with every single detector on the market that I have heard of. There is no guarantee that any one machine will do it all (none that they can live up to anyway). Anyone can claim whatever they swing is without a doubt the very finest machine in its class, but it doesn't mean that they are correct other than to say that they endorse this or that machine or brand. Within reason any machine will perform well in the right hands.
So back to what Dirt Jockey said (and very well). It will matter more how much time you spend learning the machine than the price point you meet when buying the machine. I could probably name another 10 machines that have features I like, but it doesn't mean they are right for me and the detecting I do most. It has taken me 4 different detectors to do that much and if I had to get rid of all but one...(makes me sad to think about...) I suppose I would keep my TR since as I learn it I love it more and more. It's all just opinion, but if you don't learn the machine the money spent will have been for nothing in the first place.
Lets see in a nutshell...my 2200 is my fast swing coin shooter in fairly clean parks. My 75 is all about the gold baby (operates at 13htz) and it's the only one that works great at the beach. My outback is water-proofed and goes in the lake. The Time Ranger goes everyplace except into the water, but is perfect for construction site sweeps.
Confusing enough? Yep, me too. Buy whatever machine you can afford that gets you the features you want and then spend the next year digging every pop tab and contact you can find. After a year of digging plugs and stealing all the knowledge the old timers around here are willing to part with your detector should have found enough to buy your next machine or at least put a huge dent in the price.
Good luck and happy hunting,
Doug in OR