The combination of sweet, salty, and spicy really make meats like pork and chicken sing. I dont like any of those 3 to overpower but rather balance the 3.
For beef I use very little sugar as I don't like sweet beef. I lean more towards the umami flavor profiles.
As for burning, sugar doesn't burn till 350 degrees. That is why even with copious amounts of sugar in a rub, if you smoke anywhere under that, you do not get a burnt taste.The sugar will combine with the liquid fat and help produce a bark however and also the hotter the sugar gets the more color you will get in your bark.
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