As for the sugar & maple flavor adding.
I add one or two tsp of Brown Sugar to my Tender Quick, when I cure Bacon, BBB, CB, and Dried Beef, because that is the way I was taught to counteract the sodium in cures. I don't taste the Brown sugar or the salt in my finished Products.
I have not had good luck with adding Maple flavor:
I tried Maple syrup in the cure------No added flavor.
I tried injecting Maple syrup---------Very little if any added flavor.
I did not try adding Maple syrup to the bacon right before or after smoking, because I don't want it sticky, and the Maple syrup will likely burn in the pan.
I have not tried Maple Sugar---That might work good.
As to the TQ being unsafe, I asked the USDA if it was unsafe to eat my TQ cured Bacon with the small amount of nitrates in it.
He replied, "Enjoy your Homemade Bacon". Take that however you want---That was all I got from them. Like Dan, "I'm tired of arguing about this".