Most of my PBs are models these days, but I don't use the major ones like Boyd and Cintia. I got through Bellazon and ModelHommes and find models who are followed and working, but not over-used.
The only real danger is model face. If they don't have a variety of expressions I won't use them. Generally I need at least 2 smiling icons or I click away.
You get a lot of really nice quality pics that way and it adds a whole level of variety to your choices. Sometimes it lets you find guys who wouldn't make it as actors because of being odd-looking or having a scar.