I've used thumb break, but don't like it. I prefer a friction hold.
Practice with it and you'll be ok. As you move your hand down to your weapon, let your thumb slide between the straps. It will naturally open the snap and allow you to get a "fighting grip" on the butt.
I generally don't like the "Serpa" type holsters. They're too bulky. For me, the less holster, the better. As you reach for your gun, you have to find that release catch with your finger. Maybe it's a natural reach, but I don't know.
For people engaged in a lot of physical movement, I understand the desire for a positive retaining method. However, I can turn my Fobus Kydex upside down and shake it violently and my 25 oz. gun stays right where it should be.