Singapore Sling is sweet because of the main ingredients - pineapple juice, cherry brandy and grenadine syrup. The others like Gin and Agostura Bitters just adds some kick and balance. To get the original Singapore Sling, even at the Long Bar in Raffles Hotel, you have to ask for one of the senior bartenders. I really dislike the canned drink too as it can get too sweet.
Lately, I heard the old man, descendant of the inventor of the Singapore Sling, as quit Raffles Hotel and is in another hotel.