Not all WPC’s have any particular amount of immunoglobulin to them. But where they are there, there is good reason to expect there to be value to them.
I don’t work specifically with protein filtration and so am not expert on technical aspects of the different processes, but there definitely are different methods that give different results: in other words, categorizing everything that is a “concentrate” together, and everything that is an “isolate” together, is really not so useful.
More important factors include, On mixing, is the protein fully solubilized? When that’s not the case, where there is some particulate nature, it seems that digestion can be poorer. Isolates generally do well here; some concentates do not. Is the lactose content higher than suitable for the individual, or according to desired limit on carb intake? Again, here isolates generally do well, but a given concentrate may be perfectly fine as good or better than a given isolate and may be perfectly fine. Does the protein contain intact fractions such as you mention? Here some concentrates will be better than, so far as I know, any isolate or certainly most isolates. sola