Saddler might be a little light, but Leonard never faced the type of animal that Saddler was in his prime. Saddler would rough up SRL and pound him for 15 rounds. Leonard's quickness probably bails him out of danger during the fight, but I don't doubt that Saddler would catch him and hurt him. He whupped Ped 3 of 4 fights and is one of the all time greats. Saddler vs Leonard at 135 lbs, the victory goes to Saddler by late KO or UD. Saddler vs Leonard at 147 lbs, Leonard probably wins by UD.
Leonard never fought at LW, so he'd probably be a bit too weight-drained to really be effective there. At 147 Leonard would beat him up and likely stop him in early rounds.