Most guy's can handle about 80-100lbs more when the rack pulls are started just at or slightly above knee height. If starting from 4 or less inches below top lockout position, than at least 130-150lbs can be handled. (might try shrugging from that 4" position...might amaze yourself as to just how strong those traps are). The advantage to both is the developing of more power and muscular size. Traps & back/lats get that thick, rugged look. If your a BB'er, than really no need to start lifts from the floor. Keep the reps BB'ing reps, from the 6 to 12 rep range. If starting from the floor, or even on a raised standing platform for greater DL'ing depth, pay attention to complete warm-ups and form from that floor position. That can be the danger zone for a lot of well meaning BB'ers and lifters. Rushing the weight, using too much too soon, can also cause problems.
The SLDL is an outstanding exercise for building lasting back strength. Do not round the back and keep the bar almost rubbing against the legs during this exercise. Some guy's will let the bar drift out and away from the body too far. Bad point for leverage which can result in unneeded strain and other injuries. The GM'ing is another great lower back exercise. Good Luck.