As for how the ribs are done, falling off the bone, or firm, this to me is completely based on preference. There isn't a "right way". Myself, I like it to be just before it is "fall off the bone" just for the fact that I hate it when it falls off while trying to eat/prepare them.
I too use brown sugar in my rub, but it is more to balance out the heat that invariably goes into mine. I cannot say I have a set recipe for the rub. I generally use cayenne, black pepper, smoked paprika, cumin, chili powder, mustard seed, salt, brown sugar, garlic-n-onion powder and whatever else floats my fancy that day.
The night before, I rub the meat down, and then to add even more kick to it, I coat it with Dijon mustard. This has another benefit other than flavor, and that is that it holds the rub to the meat firmly during marinating, and the cooking process. It also helps create a great "crust" layer (although it isn't crusty) when cooking.
I then smoke them at a low temperature for about 5 hours. I generally try to use apple wood, but other types work too. The smoking process to me seems to mellow out the spicy heat which is one reason why I try to make the rub rather hot. Another reason is, I generally will use a sweeter barbecue sauce when I finish the ribs. The mixture of sweet and heat is a bit tricky but very rewarding. My finishing process is basically to apply the sauce, and throw them on the grill to get some slight caramelizing but as Brook mentioned, not to burn it. I keep adding sauce and turning until I have a nice thick glaze. Falling off the bone meat will not stand up to such a process which is another reason to wait until they are just before that level.
Now I have never entered my ribs in any kind of contest or anything. For one thing, I don't believe that cooking should be competitive. With that being said, my ribs are probably in my top three jaw droppers when I make them for people. They give me the most satisfaction. You know what I mean: the satisfaction every cook gets when they hit a dish square and everyone raves about it. It is just a great feeling that you affected someone in such a way that you made their taste buds dance. I assume musicians feel the same way when they have a hit song, or when a painter makes a popular painting.