In my 30-40 holsters, only one had a thumb break...a real pain in the butt...OMO
None of my present holsters have a thumb break, and I don't every want one.
In another thread, I shared my tumble down a flight of bleachers


and the gun stayed secure.
If you use a good quality holster, retention is not a problem.
Stay armed...good holsters secure your sidearm...stay safe!