I'm not so sure I would deploy my SMB from the bottom in all cases. If I couldn't find my buddy at the beginning of the dive, and if I estimated my ascent time would be short enough--say, my depth is 60 feet--I think I might search for one minute and then waste no time beginning my ascent and focus on maintaining a steady ascent rate of 30-60 fpm until I reached the surface--omitting the safety stop. I'm well practiced at deploying an SMB, and yet it still takes me a good 15 seconds or so. While I'm fiddling with the SMB, are the boat and I getting farther apart?
It's a valid point, however I disagree.
MY experience, which may differ from your, is in diving in what would be considered a the very least "challenging" currents, some might say extreme.
I use a pre rigged crack bottle dsmb, probably the fastest deployment you can get - I think your 15 seconds is "ambitious". Nevertheless. Whether you deploy at the bottom, or near the surface, the deployment time is the same.
The sooner you get your marker to the surface the sooner the boat not only has a chance of seeing you, but also can establish your drift. One your marker is at the surface, then you can easily make your ascent - perhaps at a slightly slower and "more relaxed" pace, and make a stop if you wish (our views on this again may differ due to differing experiences).
If your making your ascent without your dsmb, what's to say you and the boat still aren't getting further apart? They have no way of knowing you're on the way up?
For a practical experience standpoint (as opposed to hypotheticals) the last time I departed a reef in current, (about 4 months ago) it took around 10 - 13 minm to get to the surface from 25m - we were hindered on the way up with an annoying down current, and we all (3 of us) took our precautionary SS
* of 5mins. By the time we surfaced we were nearly 1 mile off teh reef - with our chase boat waiting for us, having followed our drift.
* We always make stops (unless it's a really shallow bounce, which this dive hadn't been), because we dive in an extremely remote location and the nearest chamber is 8 - 12 hrs away PLB's are no use (if you could register them anyway) in my area - you rely upon making yourself seen by the pick up boat