Always lots of opinions on DL. I do lots of DL variations for powerlifting and the key is to try everything more than once and you'll know where you feel the different exercises the most. I've done every lift mentioned in this thread and more, each for several weeks, trying to improve my max deadlift. Stiff legg DL are good for the hams and the lower back. It all depends on the wieght and the reps, and your body structure. I will do SLDL from the bottom to about my knee for reps to target just hams and minimize the lower back. If I want to cream my lower back I'll do SLDL off of a platform for for doubles or singles very heavy. This hits your lower back because you start out with it at a leverage disadvantage, vs. regular stance. So at the start it's hams and back and about mid way it's mostly back. For instance, I'll do reps with say 225 or so for hamstring work, but work up to 500+ double for lower back work. Almost forgot, one key point is to slightly bend your knee (just unlock it) if you do heavy SLDL for the lower back. That also takes the hams out more and will avoid hyperextending. I think you guys are arguing over two variations of SLDL, now that I think about it.
For me heavy conv. off a platform is the ultimate back stimulator. Sumo is more hips and less back.