OK Steve. Saw your post on the other forum also. Will answer here.
I have combo driving/fog lights mounted on a brush bar because I wanted physically large lights that have a more useful light out put.
I use my driving lights to add to the light pattern from my low beam to the hi beam area (when I have my brights on). They seem to fill that area with more light extending my sight range. I'm seeing more animals on the roadside that would not be lit up with only my high beams. I have to travel a lot at night for work so I do use these the most and feel that the money was well spent.
I have used the fogs driving in the rain & fog and like the additional light. The best use I have gotten out of them was coming down a mountain on an extremely rough narrow trail, at night, with it raining. They lit up the rocks better than any other lights I had and made the decent a little less scary.

I don't like mounting them in the holes and therefore used the brush bar. My opinion is there is not enough air intake area so why block some of it up.