I have not shot this particular rifle, but do have another 16 inch barrel 44 mag and have read some posts of their accuracy from some folks on the Marlin site.
My other short barrel carbine has skinner peep sites on it and I would feel comfortable out to 100yds with mine with no scope. With a scope, 150 or whatever you feel comfortable. Remember, the 44 magnum is a handgun round meant to be shot our of 5-8 inch barrels, so even with the short 16 inch barrel, ballistics are great for a handgun round.
I'm in Vero Beach, FL