i've read through this thread, and now i know that to help with head retention i should skip the protein rest. also i've learned that to help with head retention i should do a protein rest. another way is to add carapils/wheat. of course another way is to not add carapils/wheat.
i'm glad we were able to come together and clear this up
Interesting that you say this, as I was coming back to paraphrase what I thought we had actually kind of agreed on.
First, for those of you still upset with my thread title, let me point out that this is the longest thread I've seen on head formation/retention. Maybe the title had to tweak a few noses to get a good discussion.
Now, on to what I'm seeing as a kind of consensus. With under modified and "fully" modified grains, a short (say 10 minute) protein rest at the higher end of the band (say 128 for undermodified and 133 for modified) will break down the longer protein chains and aid in head formation. Using these grains (pilsner and possibly [based on the fact that Yooper loves Marris Otter] British pale ale malts), Carapils might be, if not a cheat, a shortcut. The use of overmodified grains, and this appears to be another way of saying "American 2 Row," is not benefited by a protein rest, and may even be harmed. The only mash step that may aid in head formation with overmodified malts is a dextrinization step (158-172) of at least mash-out length (seems to be no harm in longer). That may be captured by the mash out, but if mash out is short (as it may be for BIAB brewers who "pull out the bag and turn up the heat") this step will be less effective. Even so, the dextrinization step is not a proven winner and the combination of something like Carapils with overemodified grains is [or may be] necessary for a dense head atop the beer.
Another option for American 2 Row may be to use a slightly higher mash temperature, a little more crystal than the commonly held 10% and an over-attenuating yeast. This appears to be the "industry" practice in the US (see SNPA's 12+% C60 or Rogue's reported higher mash temps).
So, to answer my question: No, Carapils (or even wheat) is not "cheating" at all, but it may be possible to replicate the results using more "traditional" ingredients and processes.
Flame on.