I say do what you want. If you want an XT then get one. It will be a valuable learning experience.
It will take a lot of leg work to find parts. And you will be working on it (and learning) more than you will be driving it. But for many of us - that's just part of the hobby. The endless, frustrating search for dirty, broken, used parts with a 50% chance of finding something that will work for just a few more miles.....
Personally - I got off the train. I realized that I want to USE my machines. Not spend endless amounts of time fixing them and trying to find or make parts for them.
Make the decision - do you want to DRIVE the car or do you want to endlessly WORK on the car? The XT choice leads you down one path, and the newer car your parents want leads you down the other path.
My choices have led me down the path of vehicles for which I can easily (not necessarily cheaply) obtain parts (and service information), and that give me pleasure to drive. I can tell you that the XT fits neither category. It's nigh impossible to find parts for, and it's underpowered and terrifying to drive.
GD