finally have a friend's gc for a bit, so get to play melee XD--been messing around w/ edgecanceled up B, and I know it's not groundbreaking, but here's my input:
* Looks flashy as hell.
*It's not too hard to set up, especially on BF. In fact, on BF, you have 3 general areas for the bottom platforms, and 2 for the top. I'd image you have the same setups on YS and the PS, though DL64 might have too high of platforms for A (below)
_A. The ground. You can use it from the ground, go through the platform, and cancel it on the edge. It's the one that seems easiest to pull off, and leaves you least vulnerable.
_B. In the air. You have a bit more leeway in the timing/spacing to get it down, but less chance of being useful in a fight except for a gtfo move.
_C. On the platform. Easiest to perform, because you are in the most freefall (greater control of your momentum and resulting slide), which is also the downside--easiest to punish.
_D.From on the top platform, you can cancel it off the edge of the top platform, or overshoot that edge, and drift back to cancel it off the edge of the lower platform. You can also up B from under the top platform to cancel off the side.
*Also, it's a bit harder to get to cancel rather than stop on the exact edge, but you an reverse up B as well, which is much more useful most of the time.
*Doing this through people, canceling on the stage lip, and jumping back w/ a b-air/d-air is pretty sick too. I'd not use it in a match though, unless you get it wicked good--missed edge->death sucks more than missed edge->lag XD
EDIT: a practical use for this is to prevent lag from up-Bing back onto the stage--> at a certain point you can drift back, edgecancel, and be on the ledge/offstage w/o lag.