Hi Flintstock,
Guess what, today is my first day on the forum too. This place is awesome. This time last year, I was in the exact same spot as you. I was just looking into the sport, but I didn't have anyone to personally guide me. I did all my research on the internet, and ended up getting a Garrett AT Pro for my first detector, and have never regretted it. Some people would say it's expensive, but it is far from the most expensive, and you get a heck of a machine in what I would consider the mid-range on price.
The AT Pro has several detection and discrimination modes, and you can also custom set your own. I'm still new to metal detecting, so someone correct me if I'm wrong, but I would say the difference between the two is that detection gives you the ability to have a pretty good idea what you are digging, it gives you an ID of sorts before you even get a shovel in the ground. Most, but not all of the time, you can tell just by the tone, and by the number on your display, what type of metal you are detecting. The AT Pro also tells you approximate depth of the item, but mine tends to display objects a little bit deeper than they actually are.
Discrimination on the other hand, is the ability to filter out certain signals. A lot of times you will get into an area that is just full of old rusted nails and other junk. If you are getting sick of listening to, and digging up every nail, you can set your discrimination to filter out those low tones all together. Does that make sense? Also, you mentioned that you will be in old farm sites. Those are almost always high trash sites, you will have to look through a lot of rusted old junk to find the treasure. That's where a smaller coil comes into play. I switched from the standard 8"x11" DD coil to the 5"x8" because of that very thing, and I love the smaller coil. You can focus on a smaller area, and pin point those high tones much easier. It's much lighter as well, which helps the old arm a lot on those all day outings.
I also have an Ace 400, and I like it a lot too. Usually when I go detecting I'll use the AT, and the kids or wife will swing the Ace. But if I were to only have one it would be the AT, simply for the ability to take it underwater if nothing else, which I do regularly, and that is where I have found my most valuable items thus far. I wouldn't trade the ability to go underwater for anything. But Kansas is mostly dry I think, so maybe that's not a concern to you.
I can't comment on any other detectors, because I haven't used any others. No doubt there are many great choices out there. Just giving you my first hand experience, from a guy whose been doing it less than a year, but totally in love with it.
Best of luck!
