I have had some of the Gold Dot stuff...it was designed for self defense purposes, not for hunting, so why worry too much?
I bet you can get their gelatin results online...
here is the first google result that came up...
Ballistic gelatin test results : .357 Magnum 158gr Speer Gold Dot JHP [Archive] - THR
Seems less than a perfect scientific test, but there it is...
Hope that helps clarify things....you can always compare it with the 125 grain bullet's test as well...loads of people are doing their own tests now, so there are a lot of different opinions out there...I would carry it for SD, probably a good winter round