I'm basically a Garrett person, I truly enjoy the ACE 250, but I also have an MXT that I purchased roughly five years ago. The 2500 (not 2000) from Garrett is also in my arsenal. I have to say the MXT is a more versatile machine than the Garrett line. With the prospecting mode, ground lock, etc there are not many situations the MXT won't work, except underwater. I think the 2500 in all metal mode and manual ground balance might have a small edge in depth over the MXT for some ground (here in KY the ground is pretty mellow). Sorry, don't have the 2000 (it was a 2500 predecessor).
The MXT and the 2500 are both fairly heavy machines, in my opinion, and I'm usually not interested in digging more than eight or nine inches, but I have retrieved a cap gun from 14 inches of gravel using the 2500. I don't think the ACE would have seen it, but I don't know I didn't have the ACE at the time.
I mostly use the ACE, or a 1500 except when water detecting. The MXT, 2500 and some other detectors I have are used for 'special' occasions that call for more than a coinshooter. e.g. prospecting, special trip relic hunting, or multiple person hunts where I can swap out when I have interference from someone. The water machine is just used in the water.
The recommend the MXT if you'll be doing a bunch of different types of hunting, some fields, woods, prospecting, relic hunting, and coinshooting. If you're mostly going for coins/jewelry at parks, schools, and sandy beaches, I'd say the 2000 might be a good deal. I don't know what the pricing is you're look at might be, but the 2500 is still an expensive machine and I think I first saw it advertised in a 1991 ad. Of course there have been updates along the way.
Be sure to get the 5.3 for trashy ground, in addition to the stock coil. I don't think the 5.3 has been off my MXT since I first installed it.
Good luck with your purchase and we'll be looking for your posts with the finds you make.