The deluxe is already lowered from the factory 1" If i remember correctly the slammers are 2" lower than a regular softail so 1" lower than your deluxe. My abuddy the slammers on his road glide adn dropped the front 2" and all I could say after I rode it was that it rode like a truck. I could not stand it. As far as scraping and such, I'd imagine you msot definitely will.
Many of your rear lowering bolts are adjustable.Burlys allow you to adjust from stock height and up to two inches lower so you are not tied in to one setting.I am going to be installing on my bike sometime before the spring riding season hits Ohio.