I'd say the advantages are these:
1) 5-10lb lean gain in a very short time. Users report strength/weight gains as soon as the second day. Also report a diuretic effect in the first couple days as well, so the overall gain might not be as significant since you'll be losing water first.
2) Dry bulk; no water retention, therefore I'd assume the majority of the gains you get you'll keep.
3) Has intrinsic anti-e properties, so it could be successfully combined with aromatizable compounds. One log in the cycles section is running m14 with this. That should prove to be a great bulker. Although I must note, there have been 2 or 3 cases so far of people using this with 4ad and getting gyno. Why this is, we dont know right now.
4) Little to no side effects. Unlike M1T, you actually feel great while using SD. You feel like you can take on anything. (This is all anecdotal, I've never used SD). Also, bloodwork shows that liver values are only slightly elevated. Further bloodwork needs to be done to evaluate cholesterol effects. Again, unlike M1T, SD is fairly free of nasty sides. I'm not saying you should, but with the low effect on liver values, you could stack SD with a mild methyl like M4OHN and not worry (the combined liver damage would likely be much less than that of M1T).
5) Its effects allows SD to be used as a jumpstart or a finisher to a cycle. I'd see it better used as a jumpstart to a drier cycle, similar to how M1T would be used. As a finisher to a wet cycle, SD would help dry out the user and solidify gains (as well as impart some more gains probably).