While that webpage was interesting, a lot of people who do those things have agendas. His apparently are championing the .45 G.A.P. and slaying dragons. -It's good to have hobbies.
Beyond performance, the real hurdle for acceptance is perceived need. Since a lot of agencies switched over to the .40 S&W in the last few years, I don't know how many are going to be excited to jump at buying new guns for their personnel with marginal performance differences.
With the civilian market, some people avoid buying pistols chambered in .40 S&W because of the difference in cost of ammo between it and a 9mm. I'd expect the .45 G.A.P. to be pricier than the .40 S&W since it will be made in smaller quantities.
The .45 G.A.P. may make some inroads, but like the .357 Sig, it has a long way to go before it will gain wide acceptance. Since it has to compete against very well entrenched calibers (9mm, .40 S&W, and .45 ACP), I suspect that it will end up in the history bin of exotic calibers. -That is assuming no major push from the firearms industry or LE sponsorship.