There is no doubt that loops are more secure than snaps, but I have been using snap on strong side OWB holsters off duty for probably 20 years. I had issues with only one. The first I bought was a Galco that I believe they called a Super Side Snap. I remember the models were SSS and a number. I did have that one unsnap on me once or twice. I took it to a leather works shop in the city and they replaced the snaps with heavier one way snaps and I never had another issue. That was for a 4" 1911.
I have a Lou Alessi for 5" 1911 that I have had nearly as long. I also have a Matt DelFatti for my High Powers. Both of those are old and heavily used. Never an issue. In and out of vehicles and an occasional scuffle. They stayed put. I trust them.
I also have a cross draw snap on for a G19 set up for long stints sitting in a car. It was made by Privateer leather and is only about 5 years old. No issues with it.
If you look at the DelFatti and Privateer you will see that the part that folds over the belt are larger and double snap. Very secure.
My own opinion would be that if you decide to go with a snap on, stay away from cheap factory built and get a good one. It makes a big difference.
Buy once, cry once.