Question. How much weight does it take to make a difference?
Question. Which is better wheel weights or hanging weights
The answer to the first question is dependant on the second question.
Weight in the tires and wheels is primarily for traction. Weight hanging out back is primarily to counter weight hanging out front.
It's a balancing act trying to get the right benefit with the least amount of weight. Most folks just use overkill and get the job done, 50 lb of liquid ballast, 50 lb of wheel weights, and 12 lb of tire chains for each rear tire, and 200 lb of rear counterweight is generally adequate. If steering becomes a problem, lifting the front implement slightly usually cures it.
The best hardpacked snow and snow covered ice traction is available with turfs and chains. Lugged tires do not have a sufficient number of inches of tread edges to bite into hard packed snow as well as the many blocks of the turf treads, and chains supported by the wide, flat turf tread have a broader width over the rounded profile of lugged tires to bite into the snow.
Lugged tires work best in soft ground conditions. Driving across a yard with a foot of snow cover constitutes soft ground conditions where deep lugs have the advantage. Following a blower or plow while clearing a driveway constitutes hard ground conditions where turfs have the advantage.