Hi there,
I think Kevin has been taught to deploy the SMB from mid water, I have seen this done and it can be good.
Instead of shooting the bag up from the bottom and winding in 20, 30, or more metres of line, ascend free to about 10m (still well below any boat traffic you will meet - anything larger and (a)you shouldn't be diving there and (b) anything that big wouldn't see you, or be able to avoid you.
This saves winding in lots of line and messing about with reels all the way up. It does however require a bit more skill in deploying the SMB and being neutrally buoyant doing it.
One good tip is to dump your buoyancy air into the bag from your BCD - you and the bag still retain the same buoyancy so no one sinks and no one rises. you can let the bag up (it will expand and rise quicker so still no clipping on) while you hold onto it. Once it is on the surface, you can re-inflate the BC or drysuit and regain neutral buoyancy independently from the SMB.
Not a trick for beginners, but if you are using a little reel (I do, for easier storage) then it saves a whole lot of winding.
Ascent can still be controlled by watching your timepiece and depth gauge , or just the computer ascent rate indicator (easier).
Safe diving,
Will