the reputation may be at least partly forum-based
for the GDSB variety, but justified. The short-barrel variety was the first "modern" hollowpoint bullet that covered a lot of bases, in that it provided 'better' expansion at lower velocities. A few years ago, they made available the 'white paper' on this development as a PDF file.
The emphasis in the development was really about providing maximum performance suitable to shooter needs, not necessarily to provide maximum performance from a given cartridge. Further, it focused on bullet design using a new (cheaper) manufacturing technology--i.e., plated, rather than 'separate' jackets of varying type.
The performance criteria Speer used for its development really is / was a newer approach, and the product is, a newer (and arguably) better design than the Remington Golden Saber and Hornacy XTP designs.
I have PDF copies of the Speer white paper and the original "short barrel' recipes Speer published--e-mail me if you want them. However, the reloading recipes are both expanded and updated in Speer 14, so it is a manual well worth buying if you want to pursue reloading these bullets.
But, overall, it seems to me to really be about identifying a market demand and filling that niche.
Speer marketed these rounds--notably, in 38 Special and 357 Magnum--at about the same time that legal carry was expanding in the handgun gunny consciousness. IOW, the demand was building. As carry expanded into a more-general public consciousness, demand, this time by 'new' shooting enthusiasts, ramped up again.
Finally, they were (arguably) the first company to focus on, and publish, reloading information for ballistics with these bullets out of short barrels, and this information included loads that would nominally match the factory information.
Soooo--all these factors came together about four-to-three years ago: lots of new carry-ers were showing up, a lot of them were carrying short barrel firearms, and some of them were reloading. Two-plus years ago, several of us in this forum who committed to revolver carry--typically, j-frames--did a lot of testing to create "replica reloads" for practice, and that information has been posted here and there. (Googling for it in this forum--i.e., try 'GDSB,' 'Replica Reloads,' or such terms ought to bring up the information for reloading.)
...and, I suspect, that gets us to where we are today--in a postive feedback loop. As long as the bullets stay together--i.e., are shot at velocities over nominally 800 and under 1050--it works well (at least in simulation) and it's a shootable round for most users.
Jim H.