If your only holster experience is with the nylon holster, you may not realize the retention provided by quality leather or kydex holster, without a thumb break.
The number of threads started by guys asking how to "break in" their leather holsters, because they can't draw their pistol out without giving themselves a "weggie" is a very long one. I tend to think "weggie" level of retention is usually sufficient for most concealed carry use. Most kydex holsters can be adjusted to provide a similar level of retention, if you want that much.
If you need more retention than that, I'd make sure to avoid a holster with a clip on attachment as the clip attachment would probably come off your belt in those instances.