I'm going to add my two cents in here. I have a MXT Pro, I had noting but problems when I started using it because I was relying on my VDI read out. Then after I used it over and over again, it started to make more sense. I have 3 different modes (Coin and Jewelry, Relic, and Prospecting mode) and a pretty good ground balance that helps me when the ground is heavy in minerals (or even hot rock). When I'm in the city, I run Coin and Jewelry. In the sticks, I run Relic.
The thing I started to learn was that if I wanted to just scan an area and see what kind of coins were there I would look at my VDI's and just cherry pick the high tones. If I found some older wheat's or silver, I would come back when I had more time and hit it hard and listen to my tone ID's. That being said, I'm sure I missed some gold, but that being said, I have bench tested my machine and found that gold is a whisper, and I always dig whispers! NOW, just yesterday I was at an old homestead and ran Relic mode. I pulled about a thousand nails, but I also found some cool stuff in the process.
Some guys like to use VDI's for specific reasons, and some guys like to dig everything, every time. THAT is the choice that you should be making......how much flexibility do you want with your machine? I hated my friend that ran his Cibola because he would find some sweet stuff, and it was accurate, but now I can do the same and more with my XLT. Sometimes I want to coin shoot, and other times I want to hunt jewelry whilst other times I want relics. I like my options. It's like trying to compare Honda's and Harley's really. Some people are loyal to the core, but let's face it.....It's all about the hunt!
So my advice is, decide what you want to spend first, then check out some at a local shop and see what options each one has that you like (weight, sounds, coils, blah, blah, blah). Chances are you'll fall in love with the brand you choose if you do your research and don't get pushed into a sale. Good luck brother hunter!
Oh by the way, think about where you're at. I plan on hitting the Sierra's when I come home to visit and I love that mine can do prospecting mode for the gold out there in Cali!