I am a holster-holic. I open carry at work and find myself more comfortable with a retention type holster. I use a pancake style thumb break with all my work guns due to 25 + years with the T/B system...I'm used to it. Due to my addiction, I have several types of holster for each weapon. Although I train with each one, under stress I fumble simply because each one rides differently, releases differently, or is in a different position entirely.
An instructor once set up a training scenario to trigger a 'startle reflex' as he called it. It showed, when startled, I reach for a weapon at 3:00 with my thumb poised to hit a thumb break like the uniformed law enforcement officer I was for so many years. So, for me, a holster riding in the same approximate location as my duty holster that released relatively the same way was my best solution. The more radically different the holster position or release method, the longer my response/draw time.