You posted this great watch just just to torment me, right??
(Complete disclosure: As Tom knows, I have been trying to learn all I can about the Hastings for the last year after I acquired a solid 14K white example last year. The various dials remain a real mystery, so it was nice of him to begin this discussion.)
FYI, I think you mis-counted the various Hastings dials. PRESUMING that the radial indeed exists, though no one seems to own one (and I think it is shown in at least 4 different old Hamilton advertisements and in the dial books, so it must have been made at some point), and presuming that your terrific serif-enamled example was an original dial option also, though it could also be unique special order I guess. With all this in mind, in addition to the 3 known and documented blueprints that you posted, this brings the total of possible dials on the Hastings to 5, not 4. I own a white gold filled Hastings with an original dial #017, though instead of luminous the numbers on my example is filled with enamel. Though I guess this could have been a special order, somewhere I saw this listed as an option also for dial #017 (either in an ad, in a dial book, or perhaps on a variant of the original blueprint??), so this could bring the total number of potential Hastings dials to perhaps 6. This sure seems like a lot for a relatively moderate seller.
Accepting the observed (but Depression-defying) reality that the more expensive raised gold number dials outsold enamel dials, and also knowing that radial dials were popular by the large number of original radial dials still remaining on Meadowbrooks. And based upon the commenly held belief among collectors that solid 14K examples (like Meadowbrooks) were MUCH more likely to have been melted-down for their gold over the years, it amazes me that a few more radial-dialed (or serif-enameled) Hastings don't still exist, especially since the vast majority of Hastings are gold filled and likely survived. (IF I were to place a wager, I think this exploding dial was some catalog artist's fantasy creation before the Hastings was released... and then somehow the next year someone forgot to modify the line art to reflect reality... and this explains the unknown radial/exploding dial in 2 catalogs and mutliple advertisement. Because of this, I think we all need to remember that catalog art may or may not reflect reality.)
My #017-dialed enamel variation Hastings is off being spiffed-up. When it is all done, I will gladly post a photo here. I have the "before" shot, but it is not very good or even alone in the shot. THANKS AGAIN TOM!!