We still love to do the '2 hour egg' although it has been played out (they're just that incredible to eat). Chef K noted, a couple of days ago, the absurdity of this popular menu name... afterall, the egg's flavor and texture is a result of a temperature and has nothing to do with time other than the time it takes for a constant external temperature to reach the innermost part of the egg (which oddly enough, is less than 2 hours as pointed out by Hervé This). Everyone is familiar with the preferred temperatures for egg cookery... 61º or 62ºC for a whole egg depending on your partiallity... 63ºC for a firmer yet flexible yolk. There are many picture references for this method. The only problems with it are portion size (you have to serve the entire egg no matter what portion would be best in respect to the entire meal... and I know someone will suggest quail eggs, so I'm eliminating them from this equation) and that you are cooking 2 substances with differing compositions which are best at differing temperatures (of course, I am referring to the white and the yolk which do not coagulate simultaneously).
So, what is the ideal temperature for 'scrambled eggs?' Once you blend the white and yolk together, the make-up of the egg behaves much differently. The fat of the yolk becomes mixed with the white leaving the other temperature reference useless. Take a whole egg cooked at 63ºC... it's perfectly done in many ways, but scrambled eggs at 63ºC are just a wet mess.
So what's a good temperature for scrambled? I blended a few dozen farm fresh eggs with an immersion blender, and filled about 20 small cryovac bags with about 1 oz egg each. They were all placed in a thermocirculator set initially at 61ºC, then after examining one bag for each temperature, the heat of the bath was turned up in 1 degree increments. This could be done every 30 minutes or so due to the fact that cooking a small bag of blended eggs does not take as long as cooking a whole egg. Stirring and moving the bags around often helps the eggs to cook more thoroughly as well.
I ended up with this guide...
Notice how the temperature pales slightly with each increase. Still, the eggs retain a very orange color... almost the color of liquid eggs used in high volume breakfast restaurants. Around 68º or 69ºC, the eggs begin to slightly curdle.
70ºC is close to perfect... the eggs can still be poured or spooned and have a creamy texture with a strong flavor of hard boiled egg yolk (easter eggs on steroids). They are much richer than fast-cooked scrambled eggs, and lack that 'rubbery' feel (you know... like at Denny's). What a dramatic increase in perfect temperature in comparison to whole eggs. The higher temperature obviously affects the flavor as well.
If we go 1 degree above that to 71ºC, the eggs begin to coagulate enough to retain the shape of their container (the side of the plastic bag).
Although I haven't tried temps between 70º and 71ºC, I believe that perfection lies somewhere between the two. Time for cooking scrambled eggs in a water bath will obviously differ depending on the amount of eggs you ladle into each bag... but the advantage is that you can periodically move the bag around (squishing it a bit) to ensure that the eggs are cooking evenly... and although you need X-ray vision to peer inside of an eggshell, it's much easier to peer (and feel) within a plastic bag. You can also serve whatever portion you desire.
Note that the eggs were plain whites and yolks without any other substance added... salt, dairy, flavorings. Any of these should technically alter the desired temperatures. Not sure, make your own reference chart.