I have thought about this, but what do you do when the fish is played out. My concern is when slipping the hook, the fish swims off when it may not be fully recovered. I’m really thinking summer fish where water temps are warmer.
These fish are pretty freaking streamlined and able to find lies where they exert little to no effort to stay there. Those are they places we find them. Usually after I remove the hook the fish will slowly meander back out into the current and find it's own place to recover...I'm sure it knows what it needs better than I do. Sometimes a fish may need to be righted before it moves off. Sometime they just sit there for a minute or so. All this non-handling of the fish has to be less of a freakout than being encased in a net or handled by the tail for a few minutes while you are letting it "recover"...in warm shallow and less oxygenated water than where it took your fly.
What convinced me to use a net was articles written by biologist about the stress the fish under goes when playing it to exhaustion. During a prolonged fight a fish builds up lactic acid in its system, that and the stress can prove to be fatal even though it swims off seemingly unharmed.
If the encounter is going to be fatal, does it matter if it swims off after being "revived" or netted or after it is quickly unhooked? Dead is dead. I've seen one die before it could be brought to hand, and it was not a long drawn out affair either.
After breaking a spey rod trying to release one in knee deep water, I've taken to throwing them some slack line when I've got them close and hoping they come off by themselves. This can save a couple minutes of the struggle and help reduce stress. Surprisingly, it seems to work about half the time. I will try to land one of those one in a season/seasons fish to get a look at it. But usually I go for the SDR, short distance release or a quick pluck of the hook. Nobody gets hurt and no rods get broke.