The 6' doesn't pull hard at all. The only issues I've ever run into is when working gravel to pull it back up a hill. As you do you loosen the gravel up and that makes finding traction hard. You can simply raise the 3pt slightly and just pull less gravel up the hill. IMO I think the scraper is easier to pull than a BB since you are not moving as much material (the main point of a BB) but more just shaving the top layer.
Thanks Dennis and crazyal for the responses. After looking closer I see Befco doesn't make a 4' anyhow - smallest they make is a 5' and I got a price of $1250 from my local dealer the other day. LP does make a 4' but I'm thinking I like the Befco better due to the adjustable blades and steel ripping shanks. The 6' LP a local dealer had in stock was priced at only $1030 but the blades are not adjustable and the ripping shanks are an add on option. Think I'm leaning toward the 5' Befco.