Did the vet open it up and find a bunch of sand in its stomach, or are you assuming thats the cause of death. I hear people say that its horrible to use sand because they read it somewhere, or a friend of a cousins neighbor knew a guy who had a beardie die. I have never in my life actually seen a beardie get impacted with sand, and if he did I'm guessing it was because he was missing bugs and catching a tongue full of sand instead.
I'm sorry your beardie died, and I'm not trying to give people bad advice, I'm just stating my opinion on sand. I dont mind if that opinion goes against the majority. Thats the joys of the internet. People can get all angles of a discussion from different people with different opinions. At the end of the day, its up to the individual to decide what he concludes from it all.
as far as urine and pooper scoopers go, its just like a litter box. The wet stuff soaks the sand, and you end up with a easily removable chunck, as long as you keep up on doing it so it doesn't dry out and get trampled. At that point I would assume it would break apart and mix into it all, which would not be good. It doesn't get nasty or smell either unless you let it get like that. I've had beardies on sand for like 2 years straight, and when I threw it out it still looked/smelled like it did when I bought it.
As far as regular soil goes, I've thought about trying it many many times. If you give it a go, let me know how it works for you. It seems like they'd be able to get the best traction, and you could actually mound it up in places to make it look natural, where sand would quickly level out.