Switching to decocker-only? Nice. Always thought Beretta safeties were awkwardly positioned. I vastly prefer 1911 safeties. The heavy DA trigger should prevent any accidental discharges anyway.
If you are comfortable with the 1911 safety, the Beretta was actually designed to mimic the thumb movement. It takes a day or so of practice to get it, but once you familiarize yourself with this technique it's easy to repeat.
1. Place your thumb straight up with your shooting grip.
2. Swipe your thumb forward and down (swiping the slide safety)
The safety pops off with authority and your shooting grip is maintained.