"momentary displacement of the limb" does not have a unique name by convention that I'm away of. I personally don't make a distinction, if the bow is 2" different from it's profile in stave form when first unbraced, it has 2" of set. If it started with 1" of reflex, it has 1" of string follow and 2" of set. A bow with a bunch of "spring back," if you will, is more than likely a little moisture heavy, or has an elastic backing like sinew. I don't think a bow which springs back 1" from 2" of set will perform much differnent than one that springs back 2" from 2", all else being equal... "much" being the operative word here as I could make a theoretical argument to the contrary. If the belly wood can be uncompressed so easily, it ain't storing any energy anyway. The trick is in most cases all things aren't equal, again MC being the difference which will effect performance.
I posted to say there's nothing magical about a deflexed stave, whether natural or induced, other than the geometry. You could just as well add lenght or width, or overbuild, to the same effect. That is, and here's the "secret" if there is one for newbies, crushed wood robs cast and that's all there is to it. How to avoid crushed wood is the question/problem. Whether we choose design (ie. deflex or longer or wider), or crafting (moisture content and tillering technique), or materials (tension wood, dense wood) isn't the question. Again, an elk don't know how many legs a horse have. Not to say deflex doesn't have it's place, particularly in shorter bow designs.
For newbies, 1" to 2" inches of set is typical for all of my projects, and antectdotally my bows seem to have above average but not exceptional cast. I think it's a mistake to err on the side of being too careful (for a newbie), but at least as big a mistake to be too cavalier wrt how much set a particular project takes. Only because many newbies suffer from project paralysis, where they are askeared to do anything "wrong" and the consequence is they don't do anything at all. Much better to bust a few, mess up a few and keep on plugging, being just careful enough to get you a few shooters, regardless of how "good" they turn out. We learn nothing from our successes, relative to our failures.
But for seasoned hands, I see no reason other than personal preference to not strive for as little set as possible, leveraging any and all devices at hand to that end. Again, if cast is important to you (not above other requiremens obviously) a "fresh" bow is a real eye opener. Since all bows (of the same "kind") pretty much shoot the same, this is the one area I've found where a bowyer can achieve some marginal improvement in performance. Obviously this assumes optimum material and design, the things we more typcially and easily can and do control. This is the essence of the crafting, for me.
