Sixer, I don't typically use retention straps.
However, I do typically use form-fitted holsters, such as those by Sam Andrews (andrewsleather.com) and Cerise Wilson (soterialeather.com). Of course, I know and like both of them, but they also make very good holsters, that retain well without straps.
Having checked out your site, I will probably try one of yours, soon.
Looking forward to it! Excellent retention is something that every holster I put my stamp on MUST have.
Just as an example... here are a few pics with a couple of fairly heavy guns.
Baby Desert Eagle
These aren't going to be unholstered unless you intend to draw