Wouldn't you rather have protein sources high in essential amino acids and easily soluble? Collagen is very low in essential amino acids:
Here's more on gelatin/collagen:
"Gelatin, a product that is generally categorized as a hydrocolloid stabilizer, comes from the hydrolysis of collagen, an insoluble animal protein. Most food gelatin is type A, an acid extraction typically from pork skins. Some type B, or alkaline-hydrolyzed product also is used. "
I'm conceding (admiting I'm wrong) on the calcium caseinate - I was told it didn't have all the essential aminos, but from what I can find, it does. The primary difference between caseinates and whey is caseinates absorb slower than whey:
"Researchers have coined the terms "fast protein" and "slow protein" to indicate proteins that are digested rapidly and slowly, respectively. Whey protein is a fast protein. Casein on the other hand is a slow protein.
Research comparing the two proteins show that they have very different effects on protein metabolism. (Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrere B. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14930-5) Whey protein causes a dramatic but short increase of plasma amino acids (hyperaminoacidemia). Casein causes a prolonged plateau of moderate increase in plasma amino acids, due to slower gastric emptying, and perhaps its amino acid profile.
This difference in the rate and duration of increased plasma amino acids has different effects on protein breakdown as well as synthesis. Whole body protein breakdown was inhibited by 34% after casein ingestion but not after whey ingestion. Postprandial (after digestion) protein synthesis was stimulated by 68% with the whey meal and about 31% with the casein.
Now it is important to note that protein breakdown is different from protein oxidation. Protein breakdown can result in amino acid recycling without significant losses of nitrogen whereas protein oxidation is just amino acids going up in smoke (in the liver) before they even get into the blood stream.
Whey and casein have different affects on protein oxidation. Postprandial whole body leucine oxidation over 7 hours was lower with casein (272 ± 91 µmol·kg1) than with whey (373 ± 56 µmol·kg1). Leucine intake was identical in both meals (380 µmol·kg1). Therefore, net leucine balance over the 7 hours after the meal was more positive with casein than with whey. In other words, although casein did not elicit such a dramatic increase in protein synthesis, by the end of the day it had resulted in greater protein deposition than did the whey. This is because the rapid increase in plasma amino acids caused by the whey resulted in equally dramatic increases in protein oxidation.
The only reason I couldn’t agree with your bedtime protein plan 100% is that it would be even better simply to use whole protein foods, particularly meat, rather than a protein drink. Something like beef or chicken will digest even slower than casein or whey. So if you really want amino acids being released all throughout the night, pick a protein source that will sit like a rock in your stomach and take a few hours to digest."
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