Note there are actually two different builds available for Mac. This page points to the build by Simone Karin Lehmann at http://gimp.lisanet.de/ which hosts only Mac builds. There is another Mac build at the main gimp.org site by Sven Claussner. Gimp.org is the primary site for the project and hosts Mac, Windows and Unix builds. The gimp.org build according to description is basic build straight from core code with no add ons. The lisanet.de build includes some add ons and some "changes' which I have searched high and low on both sites and yet to find a definitive explanation what those changes are. I started to do a menu by menu comparison between the two but it was too much work.
My experience is that the stock build on gimp.org (the one that is NOT pointed to on this page) is more stable but YMMV. The stock build runs unchanged on Snow Leopard and higher including El Cap. The lisanet.de build (the one this page) comes in various builds that support different OS X from Tiger on up.
I'm not sure what to read into the fact that the same stock build can run on Snow leopard and higher, whereas the lisanet.de builds with the "changes" has to have custom builds for each version of OS X, and if that explains in any way why the stock build is more stable (for me).
By stable versus unstable, I mean this. The build at gimp.org rarely crashes (running on Yosemite and El Cap). The build at lisanet.de (the one on this page) will almost always crash after a certain amount of time of use, sometimes as short as 10 minutes, sometimes maybe an hour, but almost every time. Again, YMMV. I'm just reporting my experience. Obviously if you use the add ons, lisanet.de is the only choice. I suspect the basic build at gimp.org is 32-bit only, it is nearly 90 MB smaller than the lisanet.de build. On the same machine, the gimp.org build also feels to run a bit faster and more responsive on the menu and toolbars.
Last, as of this date, both Mac builds are on 2.8.14. On the Windows side, earlier this week, 2.8.16 was released with a lot of bug fixes. Hopefully we will see 2.8.16 ported to Mac soon. To be perfectly honest, neither Mac build runs as fast or stable as the Windows build running in a virtual machine on the same machine. Many times, if I know I'm going to be using it for a long stretch, I find I'm more productive firing up the Windows version of GIMP virtualized using Fusion or Parallels.