It looks like you're looking for feedback on a safari-style vest, but let me respond about the general title of "Who wears a vest?".
I cover my IWB rig with a micro fiber vest I just got from Cabelas for only $7.95. I'd call it a "golf style vest", since that's the setting where I often see them. They generally cost much more, but I figured for the price I'd give it a try as a cover garment--it works great, and fits in with my style of dress, which I'd describe as business casual. It never looks "out of place" when in places where that style of dress is prevalent.
The reason it works so well for carry is that the ribbed bottom holds it fast from slipping downward, while the upper fabric, which is ample around the waist area, gathers by the waist providing ample space and fabric to hide the pistol. I've not tried it, but it would work for OWB as well, I'm sure.
Here's a look at it: http://www.cabelas.com/cabelas/en/te...vest&noImage=0