Having had some very intense workouts with the original style Nautilis pullover machine, I witness to it's direct influence on lat building. Of course with the narrow curl grip pull down bar (right in front of you..can not miss it) as the second phase of the pullover exercise. Superior because the main resistance is on the point of the elbows, where it should be for full effect. That and the three phased Nautilis cam bearing. Once you jam yourself into the seating bench, your getting a full and complete stretch of the lat's themselves. Two or three sets were tops. But BB'ers being BB's, some decided to tweak this a bit and added other exercise to a lat workout. Big mistake which lead to overworking the lat's giving less or no results for muscle building efforts. And than these misguided BB'ers blamed the Nautilis machine as being no good.
If trying to build the lats in the conventional way (rows, chins, cables, etc) the arms will always be the weakest link, giving out before the lats can be fully worked as they should be. With the point of resistance on the elbows, that is done away with. Nautilis and other like designed pullover machines have the advantage for lat building because of the elbow placement.
The DL & STDL do not require any pulling action from the arms. The arms are holding the bar in place while the rest of the body does the blunt of the lifting. The upper body acts to keep it's self in a upright position and stable with regular DL's. While the SLDL is a extension from the core center of the body, it still is keeping a stable influence. A very broad and thick back/lats can be built from either exercise.
BB or DB pullovers come closest to a ideal lat exercise. The Nautilis machine was designed to copy the action of these exercises. Do not know if their still around, but elbow slings (with pouches) were made for cable pulls and chins, where the resistance was on the point of the elbows. Could increase the weight used greatly on any exercise done with the slings. The Ab strap, though interesting, give a shorter ROM. And seem not too functional for the purpose of lat building.
If anyone has the opportunity to use a original Nautilis pullover machine, than add SLDL's as the only other lat/back exercise to the workout. If not Nautilis than try doing DB/BB bent arm pullovers followed by curl grip BB rows (into the lower gut...holding for a second). Going for a tri set, than try straight arm pullovers, bent arm pullovers and curl grip lat machine pulldowns. Chins are a first selection over lat pulldowns if you still have the energy left to do them the right way. Good Luck.