My mali seems a lot like my bearded dragon, except she seems to be a little more excited about things like coming out of the cage to roam around, and she takes food from my fingers. But my uro had a bad life, so I thought maybe finally having an owner that cares about her might have given her a special personality. I don't know though. I'm going to research about it a little. If all mali uros are as calm and cool about things as mine, then they are definately good pets.
You should go through the uro forum. They have some really cool ideas they're working with right now. Mostly they are working with the idea of 1' of dirt as substrate so that the uros can make burrows. It's a cool idea, and I'll probably try (though with only a couple inches of dirt), but I'm not sure if I like the idea of not being able to get to your pet whenever you might need to. For now I'll stick with the normal substrates and hides and stuff and maybe experiment with dirt in the summer once I can find a good source. Basically, they have found that with dirt as a substrate, as well as higher basking temps (140 degrees) and basking spots that allow for better temperature gradients, as well as many other things, the uros grow quicker and generally seem healthier. I don't think raising them on sand or millet will make that much difference from using dirt if you keep the other things the same (temps, many hiding spots, etc.). I'm not sure though because I'm no expert at all. i think the dirt just sort of makes them seem more at home and natural. You could always also just use a normal substrate and then have a box with dirt in the enclosure for them to burrow. It would probably make it easier to clean.
-ryan